Concept:Identify the correct adverb to modify the verb "kept".
Explanation:The word "secretly" means in a hidden manner, but the intended meaning is that the idea was kept in a way that shows a tendency to conceal.
The correct adverb is "secretively", which matches the sense of being secretive.
"Secretive" is an adjective, not an adverb, so it cannot modify the verb.
"Secret" is also an adjective or noun, not an adverb.
Only "secretively" works both grammatically and contextually.
Answer:Option C: secretively