Obesity is most likely caused by a. stressing too much b. sleeping too much c. exercising too much d. eating too much

Your answer is d. eating too much. If you eat too much, fat cells will grow in your body, causing you to become overweight.

The best answer is:

"D" eating too much. 

People with low stress can still be obese. Sleep is good for you, and exercising is good in certain amounts. But it burns fat, and it doesn't make you gain weight. 

I hope this helps!
~kaikers