Hi!
It would be A, aquifer. Sorry, I can't explain it, but I know it is A.
Hope this helped!
Two cells which are in direct contact can send signal to each other across gap junction. For cells which are not in direct contact, there is a number of ways through which these cells communicate, these basically include: paracrine signalling and endocrine signalling. In paracrine signalling, a cell secrete a chemical substance which have effect on a nearby cell while in endocrine signalling, hormones are released into the circulatory system, which convey them to the target cells.
The process of heart contraction stimulates by the initiation of an electrical impulse. This electrical impulse starts in the SA node.
<h3>What is the Heart contraction?</h3>
Heart contraction may be defined as a type of physiological activity that stimulates electrical impulses which are initiated by the sinoatrial node. Systole is significantly the contraction phase of the cardiac cycle.
The SA node is a small bundle of specialized cells that is remarkably located in the right atrium. The electrical activity escalates through the walls of the atria and induces them to contract. This action finally forces blood into the ventricles.
Therefore, the SA node is responsible for the initiation of impulses that stimulates heart contraction.
To learn more about Heart contraction, refer to the link:
brainly.com/question/14353904
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C.
The information required for the calculations is very easily obtained, making this an advantage of the method.
