The correct option is B 200-page
A compound adjective is formed when two or more adjectives are joined together to modify the same noun. Further, only some compound adjectives can be used to describe a person or thing, based on the quality they describe. The given sentence speaks of a ‘novel’, thus ‘200-page’ is the apt answer. Since it explains how long the novel is. Thus option B is correct. On the other hand, the other options cannot be used because they are generally not used to describe a novel. ‘Brightly-lit’ means full of light. It cannot be used for a novel. Similarly ‘well-mannered’ and ‘level-headed’ are used for describing a person and not a novel. It means a person with good manners and someone who is down-to-earth or humble respectively. Thus options A, C, and D are incorrect.