H. I.V attacks helper T cells witch are apart of the system

they are part of the immune system dawg

"a scientist studying a whale and its surroundings would need to understand the structure of atoms in case something was negatively affecting the whale or its surroundings."

explanation:

this was from the link provided:

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.