Consider the following statements indicating a comparison between rocket and jet propulsion systems:
1. Both rocket and jet engines carry the fuel and oxidant.
2. Rockets do not employ compressor or propellor.
3. Rockets can operate in vacuum also.
4. Rockets can use solid fuels and oxidants.
Which of the statements given above are correct?
a. 1, 2, 3 and 4 b. Only 1 and 2
c. Only 2, 3 and 4 d. Only 1, 3 and 4