In this question, sentence is given with blank to be filled in with an appropriate word. Four alternatives are suggested for question. Choose the correct alternative out of the four.
He has a ______ interest in studying human psychology.

Options

A. 1) deep
B. 2) wide
C. 3) vast
D. 4) heavy

Answer

A

Explanation

deep (Adjective) : very intense or exlreme, profound, sound.
Here, deep is the right option.