Answer:
A. The number of genes on its chromosomes
Explanation:
The reason why genes are so important is because genes can be transcribed to make mRNAs, and mRNAs can then be translated to make proteins. Proteins are an integral part of life, since they regulate so many processes and functions. Therefore, the number of genes (or lack thereof) in an organism defines how the organism is going to function.
I'm not sure if there are answer choices, but water is an excellent solvent, taking along valuable nutrients with it when it travels.
In the brain especially in the eyes