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. 

The  pan-african movement  was an "emotional, cultural, psychological and ideological  movement  that began among the  african  dispora in the western hemisphere, for a closer  purpose, so that  african  people could feel secure, attain political, economic as well as psychological power visa vis other races or world regions" .