Describe how you will tell your friends that Mr. Ram uses multimedia for teaching the children in passive voice.

Correct option is B

Active Voice: In Active voice the subject is the one doing the action.
Passive Voice: In Passive voice the subject is the recipient of the action.
To convert active voice into passive voice the object becomes the subject and the subject becomes the object.
In Simple Present Tense as given in the question the structure for changing a sentence into active/passive is:
Subject + is/am/are + V1 + Object.
Object + is/am/are+ V3+ by Subject.