True because when you have a gene it replicates.
Answer:
The active smokers and those getting exposed, that is, passive smokers are at enhanced threat of bacterial infections. Getting exposed to tobacco smoke enhances vulnerability to respiratory tract infections, comprising pneumonia, tuberculosis, and Legionnaires disease.
Smoking compromises the anti-bacterial activities of leukocytes incorporating monocytes, neutrophils, B cells, and T cells, thus, demonstrating the mechanism for enhanced risk of infections.
In this case two kinds of selection might be applicable to this situation. For example, if the population of grey mice are more exposed to predators due some materials used in the dam then that would be an example of disruptive selection. But if the population of gray mice is less visible to predators and if the population grow, then it will be an example of Stabilizing selection. Basicaly meant, this type of situation is also known as codominancy or codominant type.