b
In an unisolated system, heat may enter into or escape from the system due to which entropy may increase or decrease but for isolated system we do not consider exchange of heat, so, in this case entropy will always increase as the process is spontaneous. An adiabatic process involves no exchange of heat. We also define isolated system as having no exchange of heat with the surrounding so it process in an isolated system are adibatic. The two statements are independently correct but not co-related.