Developmental Psychology

Listed below are two statements related to research outcomes in the field of Child Development. For each statement answer both questions.
Statement
Young children (3 to 4 years old) generally have a memory span of 3 or 4 items. In middle childhood (9 to 10 years old) they generally have a memory span of 7 items. Questions 1A. Could you obtain this result with a cross-sectional study? Simply answer this question yes or no.
1B. If you answered yes, explain why a cross-sectional design is sufficient and why a longitudinal design is not necessary.
If you answered no, explain why a longitudinal design is necessary and why a cross-sectional design is inadequate.
Statement
Children who are regularly spanked or hit by parents are more likely to demonstrate aggressive behaviors as adults.
Questions 2A. Could you obtain this result with a cross-sectional study? Simply answer this question yes or no. 2B. If you answered yes, explain why a cross-sectional design is sufficient and why a longitudinal design is not necessary.