The correct option is A NO CHANGE
When two things are compared, their phrases should be of the same grammatical structure. Option A is correct because the underlined phrase "writing poetry" is consistent in structure to the former phrase "writing novels", hence no change is needed. Option B is incorrect because it's a single word that does not indicate the required action 'writing'. Demonstratives like 'that' modify nouns that have been mentioned before. They don't modify gerunds. Option C is incorrect because the demonstrative modifies the gerund 'writing'. The phrase "written poetry" in option D is inconsistent with the phrase "writing novels" in terms of its grammatical structure, hence D is incorrect.