Step 1: Identify the tense and structure.
The sentence "Seema is to do it" expresses obligation in active voice.
Step 2: Convert into passive voice.
In passive, the object "it" should come first, followed by the passive structure: "is to be done."
Step 3: Complete the passive sentence.
Thus, the correct passive form is: "It is to be done by Seema."
Step 4: Eliminate wrong options.
Options (A), (B), and (D) are either grammatically incorrect or not the correct passive transformation.