People who have a college degree tend to live longer than those who do not have a college degree. this is true for both men and women, and it is true across many different ethnicities and in many different geographical regions. this phenomenon is easily explained because it has been proven that people who have attended college have lifestyles and habits that are well known to increase lifespan: they eat balanced meals, they exercise often, they consider themselves happy, and they tend to have strong relationships.

the explanation given in the argument above assumes which of the following?

a. the lifestyles and habits listed increase the lifespan of most people among different ethnicities and in different geographical regions.
b. there are other reasons that explain why someone with a college degree tends to have a longer lifespan.
c. all of the people who attend college finish and get their degree.
d. people without a college degree do not have similar lifestyles and habits to those with a college degree.
e. there are other factors that contribute to a longer lifespan than the ones listed.