Male frogs can be distinguished from female frogs due to the presence of:
A. Bulging eyes
B. Vocal sacs
C. Webbed digits in feet
D. Copulatory pad on first digit of fore limbs
E. Olive green-coloured skin with dark irregular spots
Choose the correct answer from the options given below:

To identify the characteristics that are exclusive to male frogs, we examine each listed feature:

A. Bulging eyes – Both male and female frogs can have prominent eyes; this trait is not sex‑specific.

B. Vocal sacs – Male frogs possess vocal sacs that amplify their mating calls. Females lack these structures, making vocal sacs a reliable male indicator.

C. Webbed digits in feet – Webbing is common in many frog species for swimming and is present in both sexes; it does not differentiate males from females.

D. Copulatory pad on first digit of fore limbs – Males develop a specialized pad (called the nuptial pad) on the first finger of the forelimb to grasp the female during amplexus. Females do not have this pad.

E. Olive green‑coloured skin with dark irregular spots – Skin colouration varies with species, age, and environment and is not linked to sex.

Based B and D only

To identify the characteristics that are exclusive to male frogs, we examine each listed feature:

A. Bulging eyes – Both male and female frogs can have prominent eyes; this trait is not sex‑specific.

B. Vocal sacs – Male frogs possess vocal sacs that amplify their mating calls. Females lack these structures, making vocal sacs a reliable male indicator.

C. Webbed digits in feet – Webbing is common in many frog species for swimming and is present in both sexes; it does not differentiate males from females.

D. Copulatory pad on first digit of fore limbs – Males develop a specialized pad (called the nuptial pad) on the first finger of the forelimb to grasp the female during amplexus. Females do not have this pad.

E. Olive green‑coloured skin with dark irregular spots – Skin colouration varies with species, age, and environment and is not linked to sex.

Based on the analysis, the only features that uniquely distinguish male frogs are the presence of vocal sacs (B) and the copulatory (nuptial) pad on the first digit of the forelimbs (D). Therefore, the correct choice is B and D only.