Explanation:

- Section 78: This section of the Indian Evidence Act is relevant as it pertains specifically to the proof of official documents, addressing how they can be authenticated and presented as evidence.

- Correct Answer: Option 1, Section 78

- Section 82: This section typically refers to presumption related to certain documents or facts but not about proving official documents.

- Section 71: It deals with incomplete attestation of documents, which is about how documents that are improperly attested should be proved.

- Section 74: It defines public documents rather than handling their proof. It's about what constitutes a public document.