When Designing a Study, a Researcher Is Wondering If She

When designing a study, a researcher is wondering if she should ask respondents their age. She is not sure if she would need that information to do any analysis later in the research process. She is trying to:

A) determine the correct unit of analysis for her study.
B) conduct a situation assessment for her study.
C) determine the relevant variables for her study.
D) identify the symptoms and underlying problems for her study.
E) confirm the information value.