Select the most appropriate word for the given group of words.

One who is beyond reform

incorrigible

The most appropriate word for one who is beyond reform is incorrigible.

• Incorrigible means "impossible to correct or improve."
• Incomprehensible means "impossible to understand."
• Improbable means "not likely to happen."
• Implausible means "not likely to be true or to occur."

Incorrigible is the most appropriate word for this group of words because it specifically refers to someone who is impossible to reform. The other words do not have the same connotation of being beyond help.