At which of the following elevations relative to sea level will the boiling point of water be the greatest? a. 3.1 km c. -123 m b. sea level d. 127 m

The boiling point of water, or any other liquid, is mainly dependent on the surrounding atmospheric pressure. 
A liquid boils only when its own internal pressure is equal to the surrounding atmospheric pressure.

Since pressure is inversely proportional to elevation (pressure decreases as altitude increases) and since pressure is directly proportional to boiling temperature, therefore, boiling temperature is inversely proportional to altitude.
i.e. In higher places, water boils at lower temperature.

Based on this, the greatest boiling point of water will be at the lowest elevation from sea level.
The answer is: -123 m

Ibelieve y y even though i've only taken chemistry for one year

Sorry i dont understand the question can you rephase it?