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.
The answer is D
Hope this help
Thermodynamics is the study of energy and it changing forms, hope this helps.