Answer:longitudinal design
Explanation: we need to know what is longitudinal design. By definition,
longitudinal design is the study of variables or group of variables which have similar cases and repeated over a long on short period of time. This cases happened between a similar group( teenage girls ), and it happened repeatedly over a long period of time, so this will require a longitudinal design.
Yes, Some Have The Same Body Cells Some Have Different Body Cells.
There is external and internal so I'll list th external. The most important is skin then mucus, sweat or secretion, hair, nails and tears which are all part of the integumentary. Some internal defenses are white blood cells and T cells.
