A: In frog, sinus-venosus is present.
R: In mammals and birds are remnant of sinus venosus has taken part in the formation of SA node.
A. IF both assertion & Reason are true and the rason is the correct explanation of the assertion
B. If both assertion & reason are true but the reason is not the correct explanation of the assertion, then mark
C. If assertion is true statement but reason is false, then mark
D. if both assertion and reason are false statement
