Figure out the riddle and get Brainliest!

Who makes it, has no need for it.
Who buys it, has no use for it.
Who uses it can neither see nor feel it.
What is it?

When children are young and go to the doctor, the doctor will give them booster shots. this re-exposes the children to a dead portion of a disease to them build immunity.

Me d: which system contains the heart, blood, and blood vessels? a. muscular b. circulatory c. respiratory d. digestive which system contains the pituitary, adrenal, and thyroid glands? a. respiratory b. circulatory c. endocrine d. reproductive

Acharacteristic associated with good social health is the ability to: a. get along well with others b. recognize your achievements c. do daily tasks without getting tired d. learn from your mistakes