Answer:
C. a mountain peak
Step-by-step explanation:
Boiling occurs when vapor pressure equals atmospheric pressure.
The vapor pressure is the pressure exerted by the gas leaving the pot and those returning back. For boiling to occur, the vapor pressure must exceed the atmospheric pressure around.
At sea level, the atmospheric pressure is very high. With altitude, the air becomes thinner and atmospheric pressure becomes lower.
With increasing altitude, the low atmospheric pressure makes the boiling point lower as a result of the decreasing pressure on the vapor.
The boiling point can then easily be reached at higher altitudes.