Answer:
The correct answer will be option A.
Explanation:
The electrical impulses are generated in the sino-atrial node or SA node, a mass of cells which generates impulse in the upper atrium.
This electrical impulse transmits from the sino-atrial node to the atrio-ventricular node in the lower portion of the upper atrium through the internodal pathway- the pathway composed of atrial cells.
Once the impulse reaches the AV node, it is transferred to the ventricular portion of the heart through Bundle of His presence in the ventricular septum. This bundle of his divides into left and right ventricles through bundle branches and stimulates both the ventricles.
Thus, option-A is the correct answer.
<span>D.Oxygen will diffuse from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell). This is because cells respire constantly, as this process uses up oxygen cells will contain less oxygen than its surroundings. Oxygen moves by the process of diffusion, in diffusion a molecule will always move from a higher concentration to a lower concentration.</span>
Most climate scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect"1 — warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping.
Based on this exert, I'd say Option C
