Final answer:
In systemic circulation, the blood leaves the left side of the heart through the aorta, which provides oxygen to the body and returns deoxygenated blood to the right atrium.
Step-by-step explanation:
The circulation in which the blood is travelling away from the heart and first passes through the aorta on what side of the heart is known as the systemic circulation, which is associated with the left side of the heart. To clarify, in systemic circulation, oxygenated blood leaves the left ventricle through the aorta where it is then transported throughout the body.
The blood provides oxygen to the body's tissues and, after giving up its oxygen and picking up carbon dioxide, the deoxygenated blood returns to the right atrium of the heart through veins. Hence, the correct answer to the question is 'b. systemic, left'.