The answer for this question would be Level 2.
1. a. <span>is a possible explanation for events using prior knowledge
An inference </span><span>is a possible explanation for events using prior knowledge, therefore, inference is an educated guess which can provide a logical reasoning to an object, phenomenon or circumstance.
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<span><span>2. d. the amount of time ...
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</span>Since the amount of time can't clearly be controlled but only observed the other factors which is water, soil and type of plant can be manipulated in the study.
The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.