1. Why does the troposphere vary in thickness? A. Warmer air dissipates into the stratosphere. Cooler air is trapped in the troposphere.

B. Air turbulence in the troposphere varies the altitude.

C. Water vapor weighs down troposphere and less water vapor cause it to rise higher.

D. Cooler air contracts lowering the height, warmer air expands raising the altitude.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

idk and i also need to know where are those bio brainy acts lol

answer/// wohler;