Select the INCORRECTLY spelt word.

Omision

The incorrectly spelled word is "Omision." The correct spelling is "Omission."

Explanation of all options:

1. Opportunity: Correctly spelled. It refers to a favorable or advantageous circumstance or a chance for success.

2. Omision: Incorrectly spelled. The correct spelling is "Omission." It means the act of excluding or leaving out something.

3. Obscure: Correctly spelled. It means unclear, not easily understood or seen.

4. Obsolete: Correctly spelled. It refers to something that is no longer in use or outdated.