If one were to improve the diction, or word choice, of the phrase a big reason in sentence (6), all of these would maintain the style except a) "a driving force." b) "a huge incentive." c) "a proper stimulus." d) "a large motivation."

C) "a proper stimulus."

Explanation:

A driving force is used to express that someone has a big motivation or a big reason to do something, as well as a huge incentive, or a large motivation, it is used to express that someone has big willing on doing something, a proper stimulus is a motivation that is not necesarily big or smal, it´s just enough to make the person do the thing he has to do.

you need to include the text. we have no idea what you are referring to

in a place once known as north america, now known as panem, is a very rich city surrounded by twelve districts. every year because this very rich city, known as the capitol, is so rich and likes to think they control all the districts - which they do - there is something known as the hunger games! this is where two children, one boy and one girl from each district from the ages of twelve to eighteen, have to leave their families and compete in the hunger games, a live event that is aired on tv's all over panem. when katniss everdeen, aged sixteen from district 12, has to volunteer to take the place of her twelve-year-old sister prim after prim's name is called forth to become the 23rd member to compete in the 74th hunger games, she promises to prim that she will win! katniss doesn't believe she's coming out alive - but she's not going down without a fight.

because district 12 is so poor, katniss has been close to death many times from starvation but she's made it through it. but this is a different kind of close to death; this katniss doesn't know if she can survive.

she doesn't want to hurt, or kill anyone but when it comes down to it katniss' instinct is to survive. but when she starts to have confusing feelings about the boy from her district who is also her fellow contender, things get worse, and then she teams up with the girl from district 11 and only one person can survive. but who will it be? will her feelings get the better of her? will she let someone else win so they don't have to die? if katniss is going to win she's going to have to be brutal. she's going to have to kill!