One who cannot be corrected

A. Invulnerable

B. Hardened

C. Incurable

D. Incorrigible

Answer: Option D

Solution(By Examveda Team)

One word substitute is Incorrigible.

Invulnerable: impossible to harm or damage.
Hardened: having become or been made hard or harder.
Incurable: (of a sick person or a disease) not able to be cured.
Incorrigible: (of a person or their behaviour) not able to be changed or reformed.