From the given options, select the one that rightly substitutes the given expression:

One who cannot be defeated

Invincible

The word that rightly substitutes the given expression is invincible.

• Improper means "not in accordance with accepted rules or standards."
• Irrecoverable means "impossible to get back or recover."
• Invincible means "incapable of being defeated."
• Invisible means "unable to be seen."

Invincible is the best fit because it conveys the idea of someone or something that cannot be defeated, no matter how hard you try. The word comes from the Latin word "invictus," meaning "unconquered."