Which of the following is observed in the forelimbs of a frog?

Frogs have the ability to climb because they possess:

In the given diagram of a frog,where is the nictitating membrane located?

What will happen if the eyes of a frog are covered by paper?

Mention the relation of frogs with human life.

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: