Answer
curve c
Work Step by Step
When the second sheet has an angle $\theta = 0^{\circ}$:
All of the light that is transmitted through the first sheet is also transmitted through the second sheet since the two sheets are polarized in the same direction. However, none of the light is transmitted through the third sheet since the second sheet and the third sheet are polarized at an angle of $90^{\circ}$ to each other.
For $\theta = 0^{\circ},$ $~~~I = 0$
When the second sheet has an angle $\theta = 45^{\circ}$:
Some of the light that is transmitted through the first sheet is also transmitted through the second sheet since the two sheets are at an angle of $45^{\circ}$. Some of the light that is transmitted through the second sheet is also transmitted through the third sheet since the two sheets are at an angle of $45^{\circ}$.
For $\theta = 45^{\circ},$ $~~~I \gt 0$
When the second sheet has an angle $\theta = 90^{\circ}$:
None of the light that is transmitted through the first sheet is transmitted through the second sheet since the second sheet and the first sheet are polarized at an angle of $90^{\circ}$ to each other.
For $\theta = 90^{\circ},$ $~~~I = 0$
This corresponds with curve c
