Why has our contemporary lifestyle, with many people spending hours sitting sedentary in front of televisions or computers, contributed to a significant rise in obesity?​
a. ​because low muscle tone promotes insulin insensitivity
b. ​because blood glucose levels remain stagnant during inactivity
c. ​because humans use energy very efficiently, and less activity causes us to use less energy
d. ​because leptin is most effective when people are active?