6. Which of the following statements best describes one way that the Moon is different from Earth?
a. The Moon is not solid.
b. The Moon has no gravity.
c. The Moon has almost no atmosphere.
d. The Moon receives almost no solar light.

b. The Moon has no gravity.

the electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, x-rays, and gamma-rays.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.