Step 1: Identify the pattern in the number circles (figure 2). Each circle has two numbers in the top half and two numbers in the bottom half. In the first circle, the top numbers are 5 and 4, and the bottom-left number is 20. Since \(5 \times 4 = 20\), the bottom-left number is the product of the two top numbers.
Step 2: Confirm the pattern with the second circle. In the second circle, the top numbers are 3 and 8, and the bottom-left number is 24. Since \(3 \times 8 = 24\), the same product rule holds. (The bottom-right numbers, 9 and 11 in the first two circles, don't follow this product rule; they are simply the extra fourth entries in each circle.)
Step 3: Apply the pattern to the third circle. The third circle has top numbers 9 and 4, with the bottom-left number missing, marked "?". Using the same rule: \(9 \times 4 = 36\).
Final Answer: The missing number is 36, so option A is correct. \[ \boxed{36} \]
