<em>Smoking.
</em>
<em>Being overweight or obese.
</em>
<em>Lack of physical activity.
</em>
<em>Too much salt in the diet.
</em>
<em>Too much alcohol consumption (more than 1 to 2 drinks per day)</em>
If scientists believe that the newly discovered gene has two alleles A and a and that the alleles show incomplete dominance, the best way to prove this is to look for subjects who are homozygous with respect to the different alleles. The offsprings will all have the genotype of Aa and if indeed, the alleles show incomplete the dominance, the traits of the first generation will not manifest completely but a mixture of two will.
The correct answer is C) only some survive because variation exists
