Question

Fill in the blank with a suitable option:
No one doubted ___________ sincere in his beliefs.

• A. What he was
• B. That he was
• C. Why was he
• D. That he is

Answer 1

The correct option is B That he was

Noun clauses act as noun, here a particular trait and start with conjunctions like “that”. Hence Option B is correct. The rest of the options do not act as a noun, hence incorrect.