Q.) Entity-relation model is

(A) It describes the basic entities in the design and relation between them.

(B) Observational techniques used to understand social and organizational requirements.

(C) It is based on the idea of developing an initial implementation, exposing it uses on requirement and refining it through many versions until an adequate system has been developed.

(D) Based on an idea of developing an initial implementation, exposing this to uses comment and retiring it until and adequate system has been developed.