'The clock has struck five.' is a complete sentence and hence 'none of se' is correct answer.

As sentence contains 'our' only right word to use is 'us'. No or word is suitable.

What are you doing now?

He or she is watching a movie now.

The subject-verb agreement provides us with rules of placing a correct verb in correspondence to subject.
'Mr. Gopalan' is subject in this sentence. The subject is thus singular.
'Picks' is singular verb. Thus it is answer.
'Pick' is plural verb. Hence, it cannot be placed in this sentence.

Sentence is in present continuous tense in passive voice.
Rule :
Subject + is/am/are + being + V³ + or agents.
Gifts are being distributed among students now.

Sentence is in past tense.
Rule :
Subject + was/were + V³ + or agents.
The truck driver was held responsible for accident.

'what' is used while asking for information specifying something. Or options are not suitable.

'Will be' is used to refer to actions that will be happening in future, for which specific time is unknown. It is used as a helping verb to denote simple future tense.

'today' means present. 'is' is used with singular subject and refore is right answer.