Final answer:
A valid test is one that actually measures what it sets out to measure (option A).
Step-by-step explanation:
A valid test is one that actually measures what it sets out to measure. Validity is a concept that refers to the extent to which a test or measurement tool accurately reflects the concept it is intended to measure. This differs from reliability, which pertains to the consistency of a measure.
A reliable test produces the same results under the same conditions, but it may not necessarily measure what it is supposed to measure.
Therefore, the correct answer to the student's question is A. actually measures what it sets out to measure.
By contrast, a correlation coefficient of .50 or the presence of split-half reliability indicates reliability or aspects of it but not validity.