is will replace are because – A Tale of Two cities, is the name of a Single Book. So, it will take Singular Verb.
Hence, is written is the right usage.

Correct Option: B

is will replace are because – A Tale of Two cities, is the name of a Single Book. So, it will take Singular Verb.
Hence, is written is the right usage.

The will be used before UNICEF because – The (Def. Art.) is used before the names of organistions, parties, committees, etc.

Correct Option: A

The will be used before UNICEF because – The (Def. Art.) is used before the names of organistions, parties, committees, etc.

particularly will replace particular because – an Adv. modifies an Adj./Verb/Adj./ Clauses.
Look at the examples given below :

Hence, caring people particularly loved ones who is the right usage.

Correct Option: B

particularly will replace particular because – an Adv. modifies an Adj./Verb/Adj./ Clauses.
Look at the examples given below :

Hence, caring people particularly loved ones who is the right usage.

extensive will replace extensible
extensible (Adj.) : capable of being extended
extensive (Adj.) : thorough; dealing with a wide range of information
Look at the examples given below :
We had fairly extensive discussions. These tables are extensible.
Hence, who had an extensive knowledge of ancient art is the right usage

Correct Option: C

extensive will replace extensible
extensible (Adj.) : capable of being extended
extensive (Adj.) : thorough; dealing with a wide range of information
Look at the examples given below :
We had fairly extensive discussions. These tables are extensible.
Hence, who had an extensive knowledge of ancient art is the right usage

Use of he is not required because we are already talking about a particular boy.
Hence, will pass will replace he will pass

Correct Option: B

Use of he is not required because we are already talking about a particular boy.
Hence, will pass will replace he will pass