Fluid filled sacs in the knee are specifically called Bursa or Bursae. Bursae is plural for Bursa.
A bursa is a closed fluid filled sac that function as a gliding surface to reduce friction between tissues of the body. Knee bursitis occurs when there is irritation or inflammation in one one of the knee bursa. The procedure of removing fluid-filled sac is called bursectomy. When the bursa become infected with bacteria, this condition is called septic bursitis.
If the Earth were a disk with its surface perpendicular to the rays of sunlight, each point on it would receive the same amount of radiation. <span> However, the Earth is a sphere and aside from the part closest to the sun, where the rays of sunlight are perpendicular to the ground, its surface tilts with respect to the incoming rays of energy with the regions furthest away. Hope this answers the question.</span>
Answer: B. Rainforest
Explanation:
Because rainforests have huge canopies of trees, it is significantly harder for the plants below them to get sunlight.
