One who cannot be corrected

A. Incurable

B. Incorrigible

C. Hardened

D. Invulnerable

Answer: Option B

Solution(By Examveda Team)

One word substitution is Incorrigible.

Incurable: not able to be cured.
Incorrigible: not able to be changed or reformed.
Hardened: having become or been made hard or harder.
Invulnerable: impossible to harm or damage.