Few is a quantifier used with plural countable nouns. Little is used with singular uncountable nouns.
Few know about where the soul goes after the death.

By using "sent" a simple past tense sentence can be made. Other options make a grammatically incorrect sentence.
Kishan sir sent 100 books to South Africa yesterday.

"is contain" and "are contained" will make a grammatically incorrect sentence. "contain" is used with singular nouns. Hence "contains" is the right choice.
Neither of the biscuits you gave me contains chocolate chips.

Have you been to the White Rann of Kuchch recently?

Sentence is in present perfect tense with active voice.
Rule :
Subject + have/has + V³ + other agents.
Has Nensi ever beaten you?

Having got a telephone call, the driver turned up for extra duty.

Tiptoe --- carefully avoid discussing or dealing with (a difficult or sensitive subject).
The teacher made the naughty boy tiptoe.

Visited --- go to see and spend time with (someone) socially.
10,000 visitors visited www.angelforenglish.com last week.

Sentence is in present perfect tense with passive voice.
Rule :
Subject + have/has + been + V³ + other agents.
400 videos have been already uploaded by Angel for English on YouTube.

Preposition is a part of speech that determines the position of the subject or object in terms of its location. It often follows the verb. In the given sentence ‘cat’ is the subject and ‘table’ the object. Since ‘jumped’ is the verb the preposition will determine the location of the cat with respect to the table.If the cat is below the table it will jump ‘upon’ the table. If the cat is on the table it can still jump ‘on’ it or ‘down’ it.
The cat jumped upon the table.

Opposite of ‘Stale’ in meaning is Fresh

When you are speaking of or for yourself, use "am." When you are talking about a person or a thing (in the singular), use "is." When you are talking to a person, and when you are talking about other people or things (in the plural), use "are." Here, it is singular. Hence, is will be used.

Bellows --- a device with an air bag that emits a stream of air when squeezed together with two handles, used for blowing air into a fire.

There were a lot of people at our party yesterday.

Few is a quantifier used with plural countable nouns. Little is used with singular uncountable nouns. Students are plural countable nouns. "A few" means some. Option B is correct.
5,000 students had appeared in the exam a few students could get through.

When you are speaking of or for yourself, use "am." When you are talking about a person or a thing (in the singular), use "is." When you are talking to a person, and when you are talking about other people or things (in the plural), use "are." Here, it is singular as "A festival" is used. Hence, is will be used.

Unless -- except if.
Unless you read, you cannot pass.

With a positive sentence the interrogative part is always negative. Therefore, aren't we is the right option.

A policeman asked a girl what her name was.

If ---- on the condition or supposition that; in the event that.
If we do exercise, we will remain healthy.

For --- We often use for to introduce the person or people receiving something.
For whom do the people work and earn?

What were the girls playing at noon yesterday?

The more you read, the more you will learn.

Have is the root VERB and is generally used alongside the PRONOUNS I / You / We / Ye and They and PLURAL NOUNS. Generally, have is a PRESENT TENSE word.Has is used alongside the PRONOUNS He / She / It and Who and SINGULAR NOUNS."Monkey" is singular noun.
A monkey has a long tail.

Sentence is in present perfect continuous tense with active voice.
Rule :
Subject + have/has + been + V-ing + other agents.
Shraddha has been working since afternoon.

One of the girls was selected for national scholarship.

If ---- on the condition or supposition that; in the event that.
If Salman had married in time, his kids would have been adult till now.

At my fingertips --- readily available; accessible.
No, I don’t have the details at my fingertips (ready at hand immediately available), but you can look it up the internet.