James suffers from schizophrenia and flails his limbs wildly with excitement. This is most appropriately labeled as

Jessica and Rick are married. They both try to balance the time and energy they devote to their occupations, their children, and their relationship. They have a(n) __________ marriage.

Fill in the blank(s) with the appropriate word(s).

Which research design tests groups of subjects of different ages, all at the same time?

a. cross-sectional design b. longitudinal design c. sequential design d. age cohort design