Explanation:

- Option 1: Harness

- This is the correctly spelt word.

- It refers to a set of straps and fittings by which a horse or other animal is fastened to a cart, plough, etc.

- It can also mean to control and make use of (natural resources), especially to produce energy.

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- Option 2: Harnass

- This is an incorrect spelling.

- The correct spelling is "harness".

- Some might confuse it due to similar-sounding words, but it's not standard English.

- Option 3: Harnes

- This spelling is incorrect.

- It's missing the last "s," which makes it incomplete.

- Option 4: Harnnes

- This is another incorrect variation.

- It has an extra "n," which makes it spelled incorrectly.