6. sedentary lifestyles are harmful. sedentary lifestyles result in disease.
q. which sentence most clearly combines these sentences into one cohesive thought?
a. sedentary lifestyles are a result of harmful disease.
a. lifestyles that result in disease are harmful and sedentary.
a. lifestyles that are sedentary and harmful result in disease.
a. sedentary lifestyles are harmful and result in disease.

The sentence that  most clearly combines the sentences: "Sedentary lifestyles are harmful. Sedentary lifestyles result in disease;" into one cohesive thought is the last option listed. "Sedentary lifestyles are harmful and result in disease."

A cohesive thought in this case is a unit consisting of parts that fit together well and as a result form a united whole.  In this case, AND serves to join both parts to convey the right meaning of the two different sentences.

for example: in, he, a,from

you cant make me do anything i don't want to do michael yelled.