Some jovian planets give off more energy than they receive because of

1. fusion is taking place in their cores.
2. tidal heating is occurring.
3. they are still slowly contracting after formation.

which of the following statements about the cosmic background radiation is not true?

(a) It has a temperature of about 3 degrees K about absolute zero.

(b) It is the result of moisture of radiation from many independent sources, such as stars and galaxies.

(c) It had a much higher temperatures in the past.

(d) It is isotropic.