An EM wave of intensity I falls on a surface kept in a vacuum and exerts radiation pressure p on it. Which of the following are true?

(a) Radiation pressure is  $\frac{\mathrm{I}}{\mathrm{c}}$ if the wave is totally absorbed.
(b) Radiation pressure is $\frac{\mathrm{I}}{\mathrm{c}}$ if the wave is totally reflected.
(c) Radiation pressure is $\frac{2\mathrm{I}}{\mathrm{c}}$ if the wave is totally reflected.
(d) Radiation pressure is in the range $\frac{\mathrm{I}}{\mathrm{c}}$< P <$\frac{2\mathrm{I}}{\mathrm{c}}$ for real surfaces.

1. (a, b, c)
2. (b, c, d)
3. (a, c, d)
4. (c, d)