Answer:
It is important to read good books that have good plots. (A)
Step-by-step explanation:
The blank in the sentence is thus filled aptly by ‘that have good plots’. This is because it is grammatically correct and acceptable. A book is an object and thus the word the adjective ‘that’ goes with it. "That" is used for referring an object, person or an idea. It involves something which is already known of like books with good plots are known to people.