Explanation:

- Section 44: This section of the Indian Penal Code defines "injury" as any harm illegally caused to a person, in body, mind, reputation, or property.

- Section 51: This section pertains to an act, and when done with due care and caution, does not constitute negligence or a related offense.

- Section 52: This section provides the definition of "good faith". It refers to the due care and attention that a person of ordinary prudence would have exercised in similar circumstances.

- Section 52-A: This section is unrelated to the definition of "good faith" and instead relates to other provisions.

Option:3- Section 52, is indeed the correct choice for defining "good faith".