Which of the following is the correct process to develop a new system through a structured approach?

(a) Study the physical DFD of an existing system and develop logical DFD of the new system, and then develop physical DFD again for the new system.

(b) Study the Logical DFD of an existing system and develop physical DFD of the new system, and then develop physical DFD again for the new system.

(c) Study the logical DFD of an existing system, and develop the physical DFD of the new system.

(d) Any of these