Final answer:
Open-skill tests have lower test reliability but greater external validity compared to closed-skill tests, due to the unpredictable conditions that mirror real-life scenarios. Closed-skill tasks have higher reliability in controlled environments but may lack real-world applicability. Thus, individual performance can be evaluated, and task difficulty is independent of the test type.
Step-by-step explanation:
When considering the types of tests that have lower test reliability but potentially greater external validity, the answer would be open-skill tests. Closed-skill tests typically involve repetitive and predictable conditions, which can lead to higher test reliability because the conditions under which the test is administered are stable and controlled. However, they might not reflect the complexities and unpredictabilities of real-world scenarios, thus limiting their external validity.
In contrast, open-skill tests take place under variable and unpredictable conditions. These conditions mimic real-life situations more closely, which increases the test's external validity. Nevertheless, the dynamic nature of these tests can lead to lower reliability because performance outcomes can be influenced by the changing environment, making it harder to achieve consistent results across multiple administrations of the test.
Option 'd. none of the above' is the correct answer because individual performance can be evaluated in both closed-skill and open-skill tests, and the task difficulty is not inherently associated with the type of skill being tested.