Final answer:
The second 'a' in the NASCAR acronym stands for 'Association,' which is part of the full name National Association for Stock Car Auto Racing.
Step-by-step explanation:
In NASCAR, the second "a" in the acronym stands for 'Association.' Therefore, the correct answer is a) Association. NASCAR is an acronym that stands for the National Association for Stock Car Auto Racing. It is a sanctioning body that governs multiple auto racing sports events and is well-known for its stock car racing events held primarily in the United States.