Explanation:

- Option 1: Copulate

- The word is correctly spelled. It means to engage in sexual intercourse.

- Option 2: Ignision

- The word appears to be incorrect. It is likely attempting to refer to "Ignition."

- Option 3: Portion

- Correct spelling. It means a part or section of something.

- Option 4: Horticulture

- This word is spelled correctly. It refers to the art or practice of garden cultivation and management.

Option 2 is the incorrectly spelled word.

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