What is the primary source of fuel for the brain?
a. proteins
b. fats
c. carbohydrates
d. vitamins

it's answer C

That is Carbohydrates

Explanation:

"The brain's primary source of fuel is carbohydrates,". "Those carbohydrates are broken down into sugar in a form called glucose. Your brain uses glucose as its main source of energy."

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d

answer; both surfaces of the membrane are nonpermeable