A . Human society is the best answer :)
Answer:
A
Explanation:
they are associated with venous sinuses.this valve open one way flow of direction of the heart.
<span>Cirrus. Detached clouds in the form of white, delicate filaments, mostly white patches or narrow bands. They may have a fibrous (hair-like) and/or silky sheen appearance. Cirrus clouds are always composed of ice crystals, and their transparent character depends upon the degree of separation of the crystals.</span>
