Use structure “subject + auxiliary + past participle + by + object”
As per the given above sentence is given in Passive Voice.
Cricket was being played by the boys.

Correct Option: C

Use structure “subject + auxiliary + past participle + by + object”
As per the given above sentence is given in Passive Voice.
Cricket was being played by the boys.
Therefore , option C will be correct answer .

We can say that ,
The above given sentence is given in Passive Voice :-
Use structure “subject + auxiliary + past participle + by + object”
The beggar was laughed at by the boy.

Correct Option: B

We can say that ,
The above given sentence is given in Passive Voice :-
Use structure “subject + auxiliary + past participle + by + object”
The beggar was laughed at by the boy.
Thus , option B will be required answer .

Use structure “subject + auxiliary + be + past participle + object”
As per the given above sentence is given in Passive Voice.
The elders must be respected.

Correct Option: B

Use structure “subject + auxiliary + be + past participle + object”
As per the given above sentence is given in Passive Voice.
The elders must be respected.
Thus , required answer will be option B .

Note: We use “with” preposition with word “satisfied”
We can say that ,
The above given sentence is given in Passive Voice :-
Use structure “subject + auxiliary + past participle + with + object”
I was satisfied with his hard work.

Correct Option: C

Note: We use “with” preposition with word “satisfied”
We can say that ,
The above given sentence is given in Passive Voice :-
Use structure “subject + auxiliary + past participle + with + object”
I was satisfied with his hard work.
Thus , option C is correct sentence .

Use structure “subject + auxiliary + not + present participle + to + object”
As per the given above sentence is given in Active Voice.
His whereabouts are not know to me.

Correct Option: A

Use structure “subject + auxiliary + not + present participle + to + object”
As per the given above sentence is given in Active Voice.
His whereabouts are not know to me.
Therefore , option A will be correct sentence .