Antonym of SHALLOW

high
hidden
deep
hollow

The correct answer is C. Deep.

A shallow thing is not deep. It is not far from the top or surface. It is not as great in amount, extent, or degree as something else.

A deep thing is the opposite of shallow. It is far from the top or surface. It is as great in amount, extent, or degree as something else.

The other options are not antonyms of shallow.

A high thing is tall or elevated.

A hidden thing is not visible or not easily found.

A hollow thing is empty inside.