Why is proper business attire significant to business people?

A、Because one is regarded as the executive officer when he/she is wearing business attire;
B、Because of more business opportunities;
C、Because of high social status;
D、Because it conveys an air of professionalism, self-confidence, respectability and competency in the business you’re in. It creates a favorable impression for customers and clients, and influences them to do business with you, as well.