Which of the Following Is the Best Example of an Express

Which of the following is the best example of an express rather than implied contract?

A) The patient seats herself in the dental chair.
B) The dentist presents a written treatment plan involving periodontal surgery for the maxillary right quadrant to the patient.
C) The patient arrives at the dental office at the scheduled time for an initial appointment to have an examination of discomfort in the mandibular left quadrant.
D) The patient asks the dentist if the injection of local anesthetic will hurt and the dentist replies that she will anesthetize the patient very slowly and carefully to minimize discomfort.