The pattern can also be confirmed algebraically instead of just spotting the multiplication by eye.
Set up the relation: Let the top-left number be \(a\), the top-right number be \(b\), and the bottom-left number be \(c\). Testing circle 1: \(a=5, b=4, c=20\), and \(c/a = 20/5 = 4 = b\), so \(c = a \times b\). Testing circle 2: \(a=3, b=8, c=24\), and \(c/a = 24/3 = 8 = b\), again confirming \(c = a \times b\).
Apply to circle 3: Here \(a = 9\), \(b = 4\), so \(c = a \times b = 9 \times 4 = 36\).
The missing value is 36, confirming option A. \[ \boxed{36} \]
