What is the definition of minimum alveolar concentration (MAC)?
A. The lowest concentration of inhaled anesthetic achieved during the course of a procedure
B. The alveolar concentration of inhaled anesthetic that prevents movement in 50% of patients in response to surgical stimulus
C. The alveolar concentration of inhaled anesthetic that prevents movement in 100% of patients in response to surgical stimulus
D. The alveolar concentration of inhaled anesthetic that prevents spontaneous ventilation in 50% of patients
E. The alveolar concentration of inhaled anesthetic that prevents spontaneous ventilation in 100% of patients