Which of the Following Observations Is True Concerning Discovery

Which of the following observations is true concerning discovery?

A) It is the last stage of the civil litigation process.
B) It is one of the stages in a civil litigation but not in a criminal litigation.
C) It is often the most challenging part of civil litigation because discovery can be time-consuming and expensive.
D) It is a series of written questions that specifically identify information needed from the opposing party.