Correct Answer: Naturalize

Solution : The correct answer is option 1.

Explanation:

The first option is a verb.

Options 2 and 4 both function as adjectives.

Option 3 is a noun.

Verbs can be formed in a variety of ways, including:

By omitting the final few letters and including a suffix: Apology to Apologize, Authority to Authorize

By completely rephrasing the phrase : Frost to Freeze, Grass to Graze, Hard to Harden, Knee to Kneel,

Nature to Naturalize— by adding a suffix.

By changing the vowels in the word : Blood to Bleed, Drop to Drip -

By adding a prefix : Friend to Befriend, Fraud to Defraud, Circle to Encircle

Naturalize is the verb form of Nature.