Reason being is because a comma is essentially a pause in a sentence. Sometimes that isn't the case. However, ninety percent of the time its a pause simply think about where a pause should be in any sentence.
Answer:
The third one:
Kerouac’s use of syntax gives his writing an animated, conversational style by breaking free of traditional writing structures.
Explanation:
I just did the assignment
Answer:
1.a. the books are brought by the students
2b. the ball is played by the boys
3.b. the flowers are picked by the girl