Question

Assertion (A): In complete transposition of the great arteries, compatibility with life requires that communication exists between the pulmonary and systemic circulation.

Reason (R): In complete transposition of great arteries, the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Picture two separate loops running side by side; only a shunt lets oxygenated blood cross over.

Answer 1

The Correct Option is A

Step 1: Check the Assertion.
In complete transposition of the great arteries, the two circuits, the one that carries blood to the lungs and the one that carries blood to the body, run side by side instead of one after the other. Blood keeps returning to the same circuit it left from, so oxygen never reaches the body unless there is some mixing point, such as a patent ductus arteriosus, an atrial septal defect, or a ventricular septal defect. Without any such communication, the baby cannot survive. So the Assertion is true.

Step 2: Check the Reason.
The Reason describes the exact anatomical defect of this condition, the aorta comes off the right ventricle instead of the left, and the pulmonary artery comes off the left ventricle instead of the right. This is the standard definition of complete transposition of the great arteries, so the Reason is true.

Step 3: Link the two statements.
Because the great vessels are swapped in this way, deoxygenated blood from the body goes straight back out through the aorta, and oxygenated blood from the lungs goes straight back to the lungs, forming two separate closed loops. This parallel arrangement is exactly why the two circulations must be connected somewhere for any oxygenated blood to reach the body. So the Reason correctly explains the Assertion.

Step 4: Rule out the other codes.
The option where R is true but does not explain A does not fit, since the vessel swap is the direct cause of the parallel circulation problem. The options that call A or R false do not fit, since both are established facts about this congenital heart defect.

Final Answer:
Both statements are true, and the Reason correctly explains the Assertion. The printed answer key for this question was illegible in the source paper, so this answer follows standard cardiac physiology.