Final answer:
The psychometric property of an assessment instrument is its validity and reliability, indicating how accurately and consistently the instrument measures what it's intended to measure, such as with the Minnesota Multiphasic Personality Inventory (MMPI).
Step-by-step explanation:
The psychometric property of an assessment instrument referenced in the question is c) The test's validity and reliability. These properties are key indicators of how well a test measures what it's supposed to measure (validity) and whether it produces consistent results across different occasions and contexts (reliability). For example, a reliable test would yield similar results when administered to the same person over time, assuming the characteristic it measures hasn't changed. Validity concerns itself with the accuracy of the test, ensuring that the assessment truly reflects the concept it purports to measure.
For instance, the Minnesota Multiphasic Personality Inventory (MMPI) demonstrates reliability, as evidenced by a study where police officers' test results showed consistent trends over four years. This suggests that factors like the patient's age cultural background, or the clinician's experience do not determine the psychometric properties of the instrument; rather, these properties are inherent to the test itself.