The correct answer is Option C.
The conclusion summarizes the paragraph, but is followed by rechecking, revising and proofreading the paragraph. Therefore not being the last step in paragraph writing, Option A is incorrect.
Stating examples is a part of the illustration of the main idea of the paragraph and one of the middle stages in paragraph writing, making Option B the incorrect option.
The topic sentence is the controlling idea of the paragraph - hence option D is not the correct answer.
As mentioned above, revision and proofreading for errors in the paragraph is the last step in the paragraph writing.
Option C is the correct answer.