Select the appropriate verb forms to fill in the blanks in the given sentence:

If I ________ to renew the books, I ___________ to pay a fine.

Option 1 -> Uses simple past "phoned" but "wouldn't have" is incomplete and doesn't properly form a conditional structure.

Option 2 -> Uses past perfect "had phoned" with "wouldn't have had" - forms a proper third conditional for past hypothetical situations.

Option 3 -> "have phoned" with "wouldn't to pay" is grammatically incorrect.

Option 4 -> Mixes present tense "phone" with past tense "didn't have" - improper conditional structure.

Hence, Option 2: had phoned, wouldn't have had -> This creates a third conditional sentence expressing a past unreal situation. The speaker is imagining that if they had called to renew the books (but they didn't), they wouldn't have had to pay the fine (but they did). This structure (if + past perfect, would have + past participle) is used to talk about hypothetical past situations and their imagined results. -> correct