Answer:
<em>The correct option is A) an increase in oxygen levels, which led to the extinction of many anaerobic organisms.</em>
Explanation:
Photosynthesis can be described as a process in which food (glucose) is produced by photosynthetic organisms by using carbon dioxide, water along with light energy from the sun. Oxygen is released as a by-product of this reaction. The process of photosynthesis initially allowed for oxygen gas to get accumulated in the air. This caused the rise of aerobic organisms who required oxygen for respiration. Before the photosynthesis organisms evolved, there was not enough oxygen gas on earth to support the life of aerobic organisms.
There are two types of agricultural crop residues<span>. </span>Field residues<span> are materials left in an agricultural field or </span>orchard<span> after the crop has been </span>harvested. These residues include stalks and stubble (stems<span>), </span>leaves<span>, and </span>seed<span> pods. The residue can be ploughed directly into the ground, or </span>burned<span> first. Good management of field residues can increase efficiency of </span>irrigation<span> and control of </span>erosion<span>. </span>Process residues<span> are materials left after the crop is processed into a usable resource. These residues include </span>husks<span>, seeds, </span>bagasse<span>, </span>molasses<span> and </span>roots<span>. They can be used as animal </span>fodder<span> and </span>soil amendment<span>, fertilizers and in </span>manufacturing<span>.</span>
Answer: A. Zidovudine (Retrovir) and emtricitabine (Emtriva)
Explanation:
Basic postexposure prophylaxis (PEP) therapy typically includes treatment with one of these combinations of pharmacologic agents:
Zidovudine (Retrovir) and emtricitabine Emtriva),
Lamivudine (Epivir) and tenofovir (Viread), or
Tenofovir (Viread) and emtricitabine (Emtriva)
If the accidental exposure is especially severe, a third agent may be included.
A hypothesis should be tested by changing one variable in an experiment.
