Answer:
A
Explanation:
they are associated with venous sinuses.this valve open one way flow of direction of the heart.
<em>Photosyn</em><em>thesis</em><em> </em><em>happens</em><em> </em><em>in</em><em> </em><em>the</em><em> </em><em>plants</em><em> </em><em>which</em><em> </em><em>have</em><em> </em><em>chlorop</em><em>hyll</em><em>.</em>
Latitude is the measurement of the distance of a location on the Earth from the equator. The further away from the equator that you are the less sunlight that this location receives. ... At the Equator, the Sun's rays strike the Earth at a right angle, which makes the heat more intense and concentrated over a small area.
All choices correctly describes physical barriers. Physical barriers after composed of tight junctions wherein it is difficult for the bacteria and viruses to penetrate. Examples of these physical barriers are the skin and the mucous membranes and these work in conjunction with secretions like tears and mucus (as tears and mucus contain IgA, a special type of immunoglobulin that is secreted to fight harmful organisms).