Answer to Question 1
A
Answer to Question 2
A cross-sectional comparison involves comparing two or more groups of subjects of differing ages, such as four-year-olds versus eight-year-olds; the groups are studied at the same point in time. A longitudinal comparison studies one group across a given age range, such as a group of children from ages four through eight. The subjects' behavior would be measured repeatedly at two or more points in time. A sequential comparison is a mix of the other two, using two or more groups and following them longitudinally. For example, four-year-olds and six-year-olds might be followed for two years. All of the various scientific methods (interviews, naturalistic observation, experiments, etc.) might be employed in any of the three types of comparison.