For years, Aja prided herself in being able to recall zip codes quite well. However, in recent years, Aja has found herself unable to recall the new, extended postal codes. What is a likely explanation?

a) Aja's inability to change or adapt
b) the new nine-digit zip codes go beyond short-term memory capacity
c) because of Aja's limited intellectual capacity, simplicity works best for her
d) Aja's memory is changing as she grows older

b