A male frog can be distinguished externally from a female frog by all of the following features except
a. Presence of sound producing vocal sacs
b. Presence of copulatory pad on the first digit of the forelimbs
c. Ureters carry both sperms and urine in male frog
d. Testes are adhered to the upper part of kidneys by a double fold of peritoneum called mesorchium
1. a , b, c and d
2. a and b only
3. a , b and c only
4. c and d only