The correct answer is A. Hashes.

A hash is a fixed-length value generated from data using a hashing algorithm. Developers often publish cryptographic hashes, such as SHA-256 hashes, so users can compare the published hash with the hash of the downloaded file. If the values match, the user has assurance that the file was not altered or corrupted after the hash was generated.

This aligns with CompTIA Security+ SY0-701 topics related to integrity, cryptographic concepts, and secure software distribution.

Why the other options are incorrect:

B. Certificates

Certificates are used to verify identity, support encryption, and enable trust in public key infrastructure. They may support code signing, but simply posting a certificate is not the standard method for users to manually verify file integrity.

C. Algorithms

Algorithms define the mathematical process used for hashing or encryption, but posting an algorithm alone does not allow users to verify a specific file’s integrity.

D. Salting

Salting is commonly used with password hashing to defend against precomputed hash attacks, such as rainbow table attacks. It is not used for verifying downloaded file integrity.

Therefore, the developer should post hashes for the downloadable files.