The distributed system is a collection of (P) and communication is achieved in distributed system by (Q) , where (P) and (Q) are : (A) Loosely coupled hardware on tightly coupled software and disk sharing, respectively. (B) Tightly coupled hardware on loosely coupled software and shared memory, respectively. (C) Tightly coupled software on loosely coupled hardware and message passing ,respectively. (D) Loosely coupled software on tightly coupled hardware and file sharing, respectively.