Answer:
d. prepare/ will decorate
Explanation:
To answer this question it is helpful to break it into two separate parts. First, figure out which form of to prepare should be used. Remember that verbs must match the number of subjects. In this case, the subjects are plural because it is both Caroline and Sue. This means that "prepare" must be used because it is the verb that fits a plural subject.
Then, you need to understand what conjugation of to decorate that is needed. The second part of the sentence is conditional because it is dependant on what happens in the first part. It is also future tense because it hasn't happened yet. Therefore, "will decorate" is correct because it is the future conditional conjugation of the infinitive.
This means that d is the final answer.
