A tissue is avascular if it

Avascular tissues are tissues that are devoid of any blood supply by arteries,veins or capillaries these such type of tissues will ten d to be present right to a next highly vascular tissue through which it can revive nutrients and circulation.

I hope this might help u

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.