Evolution is a a. prediction because it makes an educated guess about events that will occur in the future. b. law because it has been proven without exception under certain stated conditions. c. theory because it is an explanation that is supported by extensive observations, experimentation, and reasoning. d. variable because it is a factor that can be changed during experimentation.

The answer is C

Explanation:

C. theory because it is an explanation that is supported by extensive observations, experimentation, and reasoning

i think it is dna, i'm not totally sure but i think it might be.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.