Hello Ishhika,

Mammals have three ear ossicles malleus, incus and stapes. But in case of frogs, only columella is present. Columella is a bone that contributes to hearing in amphibians, reptiles and birds, corresponding to the stapes in mammals.

So the option 4 is correct. So in Middle ear cavity of frog ear is columella.

I hope your question has been answered properly.

All the best!