True statements regarding MAC (minimal alveolar concentration) include:

(1) MAC is lower @ high altitudes, where ATM pressure is less
(2) MAC changes with age; it is maximal in late infancy
(3) The physical property of general anesthetics that correlates
best with anesthetic potency is vapor pressure
(4) It is assumed that brain & alveolar concentrations are equal
once equilibrium is reached

Any or all of the answers may be correct.

Since we have many new SRNAs, I'm going to encourage you guys to answer these types of questions. No one will fault you if you're wrong. I'll provide you an explanation with the answer.