Why is Tom Robinson unable to use his left arm?
A. It got caught in a cotton gin
B. He fell out of a tree and broke it
C. It was caught under a tractor when Tom was a child
D. He was born without the use of his left arm
The reason why Tom Robinson was unable to use his left arm is because "A. It got caught in a cotton gin," although it should be noted that this wasn't actually a common problem.