The thin, narrow structure of the capillaries is well-suited to their function because the capillaries
a) only carry the liquid portion of blood
b) transport substances directly to the body cells
c) require only a small amount of oxygen to function
d) have the opposite function of arteries and veins

Andrew feels good about himself. he doesn't know exactly why he is so happy, but every day he looks forward to his schoolwork and chores. "i play a game," he says. "i make a list of everything i have to get done, and then i try to finish it all before a certain time. for some reason, i feel great when i beat my time." based on this information, why is andrew happy? he gets a proper amount of sleep he eats healthy meals he has a strong family support group he regularly meets his own goals