To avoid deadlock in spooling systems, a system can ________.

a) provide considerably more space for spooling files than is likely to be needed
b) restrain the input spoolers so that they do not accept additional print jobs when the spooling files approach some saturation threshold
c) allow printing to begin before the job is completed so that a full, or nearly full, spooling file can begin emptying while a job is still executing
d) all of the above

d) all of the above