From both the plaintiff's and defense's attorneys is an optional phase of the trial. generally, it's allowed to cover an issue raised during cross-examination of a witness.
a. rebuttalb. plaintiffc. closing argumentsd. opening statements

The answer is A. Rebuttal.

Explanation:

Rebuttal consists of a kind of evidence that is usually utilized to contradict other evidence that was considered by an opposite party. This term is also used in aspects related to politics as well as public affairs.

In terms of law, there are special rules concerning rebuttal. Rebuttal evidence or rebuttal witnesses must be related to the appropriate subject concerning the evidence rebutted. If there is new evidence that has a relationship with other subjects, it cannot be admitted in rebuttal. However, a rebuttal is considered a way through which a party could introduce unexpected evidence as well as witnesses.    

answer would be b, a tariffs main purpose is to protect domestic production and jobs.