Two different inputs producing the same hash value is referred to as a

• A. Birthday collision
• B. Preimage
• C. Collision
• D. Hash inversion

Answer: (C)

Collisions in hash functions occur when two different inputs produce the same hash value. Since a hash function maps many possible inputs into a fixed-size output, such collisions are inherent. The term “birthday collision” refers to the probabilistic likelihood of encountering a collision based on the birthday paradox, not the basic definition. A preimage or hash inversion idea is about recovering an input from a given hash, which is a different concept from two inputs producing the same hash. So the best answer is collision.