Select the correct passive form of the given sentence.

My mother is watching a new serial about the life of Dr. Ambedkar.

A new serial about the life of Dr. Ambedkar is being watched by my mother.

The correct passive form of the sentence "My mother is watching a new serial about the life of Dr. Ambedkar" is A new serial about the life of Dr. Ambedkar is being watched by my mother.

The other options are incorrect because:

• A new serial about the life of Dr. Ambedkar was being watched by my mother uses the past progressive tense, not the present progressive tense.
• A new serial about the life of Dr. Ambedkar is watched by my mother does not use the verb "to be" in the passive voice.
• A new serial about the life of Dr. Ambedkar will be watched by my mother uses the future tense, not the present progressive tense.