Assertion(A):- Mendel chose a no. of varieties of garden pea as plant for his experiments Reason(R):- Garden pea has well defined characters and was bisexual

Assertion (A) is correct. Gregor Mendel, the father of genetics, chose garden pea (Pisum sativum) for his experiments due to its several advantageous characteristics.

Reason (R) is also correct and it is the correct explanation for Assertion (A). Garden pea was an ideal choice for Mendel's experiments because it has well-defined and contrasting characters like color and shape of the seeds, color of the flower, position of the flower, etc. Moreover, being a bisexual plant (having both male and female reproductive organs), it can self-fertilize as well as cross-fertilize, which made it easier for Mendel to control the mating.

So, both the assertion and reason are correct and the reason is the correct explanation for the assertion.