The correct answer is: D. Neither I nor II is implicit.
The statement “In spite of poor services, the commutators have not complained against it” does not provide enough information to determine whether or not assumption I (Generally people do not tolerate poor services) or assumption II (Complaints sometimes improve services) is implicit. It is possible that the commutators do not tolerate poor services, but they have not complained because they do not believe that complaining will improve the services. It is also possible that the commutators do tolerate poor services, or that they do not believe that complaining will improve the services.
In order to determine whether or not assumption I or II is implicit, we would need more information about the commutators’ attitudes towards poor services and their beliefs about the effectiveness of complaining.