Answer:
Longitudinal studies and cross-sectional studies are two different types of research design. In a cross-sectional study you collect data from a population at a specific point in time; in a longitudinal study you repeatedly collect data from the same sample over an extended period of time.
Explanation:
Capillary walls are thin and are composed of endothelium
Answer:
Snuff is a type of tobacco that is smokeless. It is inhaled and sniffed, not smoked.