The circular dichroism spectra of three proteins $P$, $Q$, and $R$ are given below:

Choose the correct combination.

1. $P: \alpha- \text{helix}, Q: \beta- \text{sheet}, \text{ and } R: \text{Random coil}$
2. $P: \beta- \text{sheet}, Q: \alpha- \text{helix}, \text{ and }R: \text{Random coil}$
3. $P: \beta- \text{helix}, Q: \alpha- \text{Random coil}, \text{ and }R: \text{sheet}$
4. $P: \beta- \text{Random coil}, Q: \alpha- \text{helix}, \text{ and }R: \text{sheet}$