The correct option is D Second Conditional
The Second Conditional is used to refer to future actions that are dependent on the result of a past condition, but when there is a very small possibility of the condition being satisfied. In fact, this condition is often used to talk about hypothetical possibilities; ones that are unreal. The structure for the first conditional is: if + past tense, would + verb. In this case, the verb is 'to be' and thus the sentence adheres to the structure of the Second Conditional - i.e, Option C).