Assertion: In human male, testes are extra abdominal and lie in scrotal sacs.
Reason: Scrotum acts as thermoregulator and keeps testicular temperature lower(2- 2.5°C lower than the normal temperature necessary for  spermatogenesis.

Both Assertion (A) and Reason (R) are correct and R is the correct explanation of A.

The correct answer is Option (1) -Both Assertion (A) and Reason (R) are correct and R is the correct explanation of A.

The assertion is true. The testes are situated outside the abdominal cavity within a pouch called scrotum. In adults, each testis is oval in shape, with a length of about 4 to 5 cm and a width of about 2 to 3 cm. The reason provided is that the scrotum acts as a thermoregulator, maintaining the testicular temperature lower than the normal body temperature by 2-2.5°C, which is essential for spermatogenesis. This is also correct and serves as the proper explanation for why the testes are located in the scrotal sacs rather than within the abdominal cavity.