Heart disease, lung disease, and diabetes can be considered
a. lifestyle diseases
b. hereditary diseases
c. contagious diseases
d. environmental conditions

A. Lifestyle diseases Because what you do in your life can put into effect into these diseases. If you don't eat right or exercise you can get heart disease. If you smoke you can get lung disease.

The answer is A!
heart disease could come along if you don't exercise your heart and make it stronger.
lung disease could come along if you smoke drugs "imagine your lungs become the color grayish blackish" not healthy:/
and diabetes depends on your diet. If you eat too much sugar or not the right types of foods your insulin and glucose levels would be unstable 
see the similarities of all of these is that they are all lifestyle choices. 
So its up to you to be healthy or not:)
if this wasn't confusing and it helped you 
then don't forget to 
MARK ME BRAINLIEST! :D

Ithink it's d or it can be itger