While Deleting All Files Beginning with the Letter a There

Multiple Choice

While deleting all files beginning with the letter a there was still the file Access.txt left. Assuming that it had the correct ownership, why was it not deleted?

A) Files with extensions need a different treatment.
B) rm had to be called with the option -R to delete all files.
C) The file Access.txt was probably opened by another application.
D) The file Access.txt was hidden.
E) Linux file names are case sensitive.