The correct option is C A is correct but R is incorrect
Initially in the fetal stage, the testes remain inside the abdominal cavity but, right before the birth the testes descend into the scrotal sac.
This descend is necessary for the process of spermatogenesis which requires a lower temperature than the normal human body temperature. Scrotal sacs maintain a 2-2.5 degree lower temperature than the normal body temperature.
Area occupied by the prostate gland and seminal vesicles is not the reason for scrotal descend.
Therefore, assertion is correct but reason is incorrect.