Assertion: Lub is a heart sound which is produced during each cardiac cycle.
Reason: It is associated with the closure of the tricuspid and bicuspid valves.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
Explanation:
Lub and dub are two heart sounds, which occurs due to the closure of cuspid valves and semilunar valves respectively. Lub is the first heart sound which is formed due to closure of atrioventricular valves at the beginning of ventricular systole. It is low pitched of long duration (0.15 sec).