Final answer:
Option (c), The term referring to the accuracy with which a test is designed to measure what it is supposed to measure is 'validity.' Validity requires that a test not only produces repeatable and consistent results (reliability) but also accurately reflects the construct it intends to measure.
Step-by-step explanation:
The term that refers to the accuracy with which a test fulfills the function for which it was designed is validity. Validity is concerned with how well a test measures what it is supposed to measure. While a test can be reliable without being valid, for a test to be valid it must also be reliable. This means the test must produce consistent results under the same conditions (reliability), as well as accurately reflect the specific concept it's intended to measure (validity).
Reliability is the consistency of a measure; a test is reliable when the same results are produced under the same circumstances. Several types of reliability exist, including internal consistency and test-retest reliability, among others. However, mere consistency does not imply that the measure is correct. For instance, a kitchen scale that consistently measures incorrectly due to miscalibration is reliable but not valid.
Therefore, when assessing the appropriateness of a test for its intended use, it's essential to establish both its reliability and its validity to ensure that it accurately and consistently measures the concept or thing in question.