Which of the statements about inquiry below is true?
选项：

A:Inquiry is a diagnostic method that a doctor takes medical history of a patient by inquiring the patient of relevant people systematically, conducts analysis and make clinical judgment. ;
B:Inquiry is the road sign and clue for disease diagnosis as some diseases can be diagnosed through inquiry.;
C:Inquiry is the key moment to establish a harmonious doctor-patient relations. Successful inquiry makes patients feel that a doctor is amicable, facilitates the doctor-patient cooperation and leads to better diagnosis and treatment.;
D:All of the above