The answer is C) chromosome :)
Fats are used for energy after they are broken into fatty acids. Protein can also be used for energy, but the first job is to help with making hormones, muscle, and other proteins. Broken down into glucose, used to supply energy to cells. Extra is stored in the liver.
The carbon lives in the plant or animal and when it dies, nitrogen sinks into the soil which is used as nutrients for plants.
Genetic traits that survive through selection increase throughout a population.
