Option 1 -> "had" is past simple, used in second conditional for hypothetical situations (If I had... I would...).
Option 2 -> "will have" is incorrect because we don't use "will" in the if-clause of conditional sentences.
Option 3 -> "has" is present simple but third person singular, which doesn't agree with the subject "I".
Option 4 -> "have" is present simple, first person, correctly forming a first conditional sentence.
Hence, Option 4: have -> This sentence uses the first conditional structure (If + present simple, will + base verb) to express a real possibility in the future. The if-clause requires present simple tense, and since the subject is "I", we use "have" -> correct