Which sentence is written correctly?

a) if i be a butterfly, i'd flap my wings all over the world.
b) if i am a butterfly, i'd flap my wings all over the world.
c) if i was a butterfly, i'd flap my wings all over the world.
d) if i were a butterfly, i'd flap my wings all over the world.

D) If I were a butterfly, I'd flap my wings all over the world.

Explanation:

In this sentence, the best past tense is what is required. So, were is appropriate to be used in the sentence because it refers to second person singular and plural. Furthermore, when a scenario is created to explain a past event and the secon person was not involved, were is the suitable past tense to use so as to involve the second person.

the objective should be switched