Black or dark gray shapeless masses of thick vapor, formed at middle levels or very near to the surface of the earth that are extremely dense and opaque to the rays of the sun are called _____?

Nimbus clouds

The correct answer is Option (2) → Nimbus clouds

Nimbus clouds are dark or black, thick, shapeless masses.

They are very dense and opaque, often blocking the sun’s rays.

These clouds are commonly associated with rainfall.