Since he doesn't drive, Sheldon has been commuting to campus on the Metro for many years. Every morning he takes the $7$:$00$ a$.$m$.$ train that is scheduled to arrive in Pasedena at $8$:$15$ a$.$m$.$ He has to be at work at $8$:$45.$ Although Sheldon would like the subway to arrive in Pasedena on time, he knows from his experience as a commuter that it is more likely the train will be $3$ minutes late, so this situation reflects his $q,$ level of service for the Metro because if this wasn't $"$ okay." then Sheldon would choose to take a taxi to work instead.

A$.$ desirable

B$.$ adequate

C$.$ functional

D$.$ utilitary