Explanation:

- The sentence uses a conditional structure. It refers to a hypothetical situation in the past.

- "Would have fined" suggests an unreal past condition, needing a past perfect tense in the conditional clause for correct grammar.

- Option 1: "he came to know"

- Grammatical structure matches a simple past tense.

- Does not match the past perfect needed for unreal past condition.

- Option 2: "he comes to knew"

- Incorrect tense form; mixes present and past tenses.

- Option 3: "he had come to know"

Correct substitution: "he had come to know."

- Option 4: "No substitution required"

Not relevant option as the sentence needs improvement.