Final answer:
The number of different answer keys possible in a multiple-choice test with 8 questions and 4 choices for each question is 65,536.
Step-by-step explanation:
In this multiple-choice test, there are 8 questions and each question has 4 choices (a, b, c, d). To find the number of different answer keys possible, we need to calculate the total number of possibilities for each question and then multiply them together.
For each question, there are 4 possible choices. Since there are 8 questions, we multiply 4 by itself 8 times, which can be written as 4^8. Calculating this, we get 65,536. Therefore, the correct answer is a) 65,536.