I believe it is idiopathic.
Genetic mutations increase variety by adding uniqueness to the world. Genetic mutations can come in all shapes and sizes based on the chromosomes in cells. Perhaps someone was born with one blue eye and one green eye, or perhaps they have hair a certain, unusual color. Genetic mutations add variety to the world by making sure everyone isn't the same!!
The answer is C=territoriality
This is so because Al's cat may have seen another cat in his 'home'. Cats don't like it when other cats trespass into their territory, so this is a way of marking it.
The nitrogenous bases in DNA are adenine, guanine, thymine, and cytosine.
The nitrogenous bases in RNA are adenine, guanine, uracil, and cytosine.
So the base in RNA that is different than in DNA is uracil.
Hope this helps.