
The problem involves understanding the relationship between the length of a pendulum \(L\) and its time period \(T\). The time period \(T\) of a simple pendulum is given by the formula:
\(T = 2\pi \sqrt{\frac{L}{g}}\)
Squaring both sides, we get:
\(T^2 = 4\pi^2 \frac{L}{g}\)
This can be rearranged to express as:
\(\frac{1}{T^2} = \frac{g}{4\pi^2} \cdot \frac{1}{L}\)
This expression shows that \(\frac{1}{T^2}\) is inversely proportional to \(L\). Therefore, the plot of \(\frac{1}{T^2}\) versus \(L\) should be a hyperbolic (curve downwards). Option D correctly represents this inverse relationship.

Hence, the correct answer is D.