The first polarizer will reduce the intensity by a factor of $1/2$ . The second polarizer will reduce the intensity by a factor of $\cos^2 45\circ = 1/2$ . So, the transmitted light intensity will be $\left(1/2\right) \cdot \left(1/2\right) \cdot 100 \% = \boxed{25 \%}$ . Therefore, answer (D) is correct.

Solution to 2008 Problem 16