A is the correct answer my friend :)
During adolescence, puberty begins when the pituitary gland increases the amount of growth hormone in your blood stream.
Hope This Helps!
Communicable and infectious diseases are those where they can spread from one person to another, from one social group to another. There are many communicable diseases (an example being measles which has made a comeback in the US due to parents not vaccinating their children).
3: immune system
4: antigens
1: not sure but maybe T-cell
2: how germs get inside our bodies
