Answer: D
\(a \propto \frac{1}{b^2}\) i.e., \(a = k \cdot \frac{1}{b^2}\) [where \(k\) is a non-zero constant] i.e., \(ab^2 = k\) i.e., \(b^2 = \frac{k}{a}\) i.e., \(b = \pm \sqrt{\frac{k}{a}}\) i.e., \(b \propto \pm \frac{1}{\sqrt{a}}\) [since \(k\) is a non-zero constant]
\(a \propto \frac{1}{b^2}\) i.e., \(a = k \cdot \frac{1}{b^2}\) [where \(k\) is a non-zero constant] i.e., \(ab^2 = k\) i.e., \(b^2 = \frac{k}{a}\) i.e., \(b = \pm \sqrt{\frac{k}{a}}\) i.e., \(b \propto \pm \frac{1}{\sqrt{a}}\) [since \(k\) is a non-zero constant]