Why is it important to establish a trusting relationship with a client?

Why is it important to establish a trusting relationship with a client?
 
  A) It helps to increase the self-esteem of the practitioner and makes him/her more effective.
  B) It is necessary in order for the practitioner to go further with exploration and gain more information.
  C) The client may decide to see another practitioner in the future, and it is important for the client to have a good experience now.
  D) It is important for the client to see that the differences between him or her and the practitioner are not important.