He declared his______ (Choose the correct option)

Here, the verb declared needs a noun object, meaning it should express what he declared.

The word “his” also requires a noun after it. “Innocence” is the noun form of the word and correctly expresses the idea that he claimed he was not guilty.

Other options are incorrect because:

• “Innocent” is an adjective, so it cannot act as an object.
• “Innocently” is an adverb that describes a manner, not a thing.
• “By innocent” is grammatically incorrect and does not make sense in the structure.