Switch A and D, but other than that your answers are correct.
An astronomical body is an object in space.
A comet is a celestial object consisting of a nucleus of ice and a stream of gas and dust.
A moon is an astronomical body that orbits around a planet.
A galaxy is a system of start held by gravitational attraction.
Mammals. I am no scientist, but I think that they are closer to mammals due to the fact that they are warm-blooded, and they raise their young. Reptiles are cold blooded and usually leave their offspring to fend for themselves.
Because proteins are complex molecules, the body takes longer to break them down