The correct answer is B. Adding an idea
Step-by-step explanation:
The word "moreover" is a synonym of "additionally", "also" and "furthermore"; this implies, this word is mainly used to add information or ideas that are related to previous sentences. For example, in "Jane wrote four iconic novels; moreover, she was a professional athlete" the word "moreover" serves as a transition or linking word to add previous information about the same person. According to this the word "moreover" is used for adding an idea.