An algorithm should output "OK" if all numbers in a list are non-zero. What is a valid test for this algorithm?

The correct choice involves input where one or more numbers in the list are zero, which directly tests the algorithm’s ability to recognize zero as a condition that should disallow the output of "OK." Since the algorithm is designed to output "OK" only if all numbers are non-zero, providing any zero value in the list gives a clear scenario to assess whether the algorithm functions correctly when it encounters zeros.

When using this choice, the algorithm should not output "OK" because there is a zero present in the input. This helps verify that the condition for successful output (all numbers being non-zero) is effectively checked by the algorithm, ensuring it behaves as expected in this specified case. Additionally, this input case indicates the algorithm's failure path, demonstrating its capacity to handle incorrect scenarios by providing an appropriate response.

Evaluating the other choices reveals that they do not challenge the algorithm in the same way. For example, the options containing only non-zero integers would lead the algorithm to output "OK," which does not test its logic concerning the presence of zero. Thus, the designated choice is crucial for validating the algorithm's conditions and overall functionality.