Which of the following statements regarding hydrogen bonding is true?

a. a hydrogen bond forms when a positively charged hydrogen ion bonded to a negatively charged atom.

b. hydrogen bonding is possible when hydrogen is in a polar covalent bond.

c. a hydrogen bond forms when a partially negative hydrogen is attracted to a partially positive oxygen.

d. a hydrogen bond is a type of polar covalent bond.

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

c. the initial amount of money placed in the savings account

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.