Final answer:
Content validity is key in a legal setting when a test's defensibility is challenged, as it indicates the test accurately spans the range of job requirements and is non-discriminatory.
Step-by-step explanation:
The type of validity that is legally defensible if challenged in court is B) Content validity. Content validity refers to the extent to which a test represents the entire range of possible items the test should cover. In legal settings, especially in employment law, if a test is challenged for its employment selection criteria, it is critical that the test accurately reflects the job requirements and duties; this is the essence of content validity. Demonstrating content validity can help show that the test is fair and non-discriminatory. Additionally, evidence of empirical validity, which concerns the correlation of the test with actual job performance, can also be required. However, content validity is often the primary focus in legal challenges to ensure the assessment method is appropriate for the decisions being made.