Answer:
genetics
Explanation:
calico cats must also inherit a gene unrelated to the X and Y chromosomes that codes for white fur. Because male cats have one X chromosome with code for black or orange and one Y chromosome with no color genes, they cannot technically be calico. About one in every 3,000 calico cats is born a male, and, unfortunately, don't live as long as female calicos due to their genetic abnormalities. XXY Syndrome renders male calicos sterile and can be the root cause of many other health problems
The answer is to this question is A
Answer: Louis Pasteur
Louis Pasteur in 1860s, proposed germ theory. The theory was based upon the fact that diseases are caused by the microorganisms. He was officially the first to publish his work.