Explanation:

- Option 1: "When I will have a degree"

This sentence indicates a future event, but it doesn't align with the structure needed for a hypothetical or contrary-to-fact situation.

- Option 2: "If I am having the degree"

This phrasing is awkward and ungrammatical for this context. Present continuous tense is not suitable here as it implies a current ongoing action, not a hypothetical situation.

- Option 3: "No substitution"

The original sentence is ungrammatical. The phrase "If I would have a degree" is incorrect in standard English conditionals.

- Option 4: "If I had a degree"

This option uses the correct structure for a second conditional sentence, which is used for hypothetical situations in the present or future.