A grand jury primarily decides whether to ______.

The primary role of a grand jury is to determine whether there is sufficient evidence to formally charge an individual with a crime, which is accomplished through the issuance of an indictment. This process does not involve deciding guilt or innocence, which is the responsibility of a trial jury.

In a grand jury setting, members review evidence presented by prosecutors and assess whether it substantiates a criminal charge. If they find enough evidence, they issue an indictment, which allows for formal prosecution to move forward. The grand jury's function is investigative and protective in nature, aimed at preventing unfounded prosecutions.

Considering the other options:

• A trial jury determines guilt or innocence, which is beyond the gran jury's remit.

• Taking a plea is a matter that occurs post-indictment during plea negotiations, unrelated to the grand jury's functions.

• Summoning the offender is a procedural step that may happen in the context of a trial or evidence gathering, but it is not a grand jury's primary responsibility.

Thus, the correct answer reflects the grand jury's essential role in the legal process by focusing on whether to issue an indictment based on the evidence presented.