The NASA mathematician Mary Jackson, when offered an opportunity to train as an engineer, had to petition the city of Langley to get permission to attend courses at nearby racially segregated Hampton High School,
which only after a special court hearing, they allowed her to attend.
A) which only after a special court hearing, they allowed her to attend
This gives us the meaning as though the Hampton high school were the one hearing the case which is not the case hence out
B) allowing her to attend only after a special court hearing
it's conscice and no obvious meaning error is found
C) which she attended only after a special court hearing that they allowed
We are not able to pin down who allowed the mathematician was it the court or the school
D) allowing her only to attend after a special court hearing
only to attend is not conveying the right meaning since it conveys she has to hear the meeting
E) which she was allowed to attend only after a special court hearing
Here which is correctly pointing back to the school and the meaning is perfect
However i chose it over E since B conveyef the meaning in a conscice manner and which usually means trouble
Therefore IMO B