What is defined as a situation where two different inputs yield the same output?

The correct answer is a situation described as a "collision." In cryptography, a collision occurs when two distinct input values, such as different messages or data, produce the identical output when processed through a specific hash function. This phenomenon is significant because it undermines the uniqueness property that cryptographic hash functions are supposed to provide; ideally, each unique input should map to a unique output.

Understanding collisions is crucial for cryptography and data integrity since they can lead to vulnerabilities where an attacker could substitute a legitimate input with a malicious one without detection. This concept is fundamental in cryptography, as robust hash functions are designed to minimize the possibility of collisions occurring.

The other terms present different cryptographic concepts: transposition refers to a rearrangement of the order of elements in the data, convergence is not a standard term in this specific context, and substitution involves replacing elements of the input with other elements in a systematic way. These concepts do not relate to the specific scenario described regarding two distinct inputs yielding the same output.