Answer:
a. it is used only in drama.
Explanation:
Statement of option "a" is false, dialogues are widely used in drama, however, they are not limited to this genre only, and it is also used in Adventure, Mystery, Science Fiction, Fantasy, Historical fiction, Contemporary fiction and nonfiction genres.
The other options, on the other hand, are true: dialogue is a conversation or other form of discourse between two or more people (option b), it is used in many types of writing (option c) and its main purpose is to reveal the characters' personality, thoughts, views, and feelings and to draw the reader into their lives (option d).
