b. At higher elevations, it would take longer to hard boil an egg, because there is a lower boiling point, so the egg is boiling in water at a lower temperature.
Explanation:
The best answer from the given choices is that, at higher elevations, it would take longer to hard boil an egg, because there is a lower boiling point,
so the egg is boiling in water at a lower temperature.
Boiling point is simply the pressure at which the vapor pressure of a liquid is equal to the atmospheric pressure.
At higher elevations, the atmospheric pressure is low and it would require little heat to boil water and turn it into vapor.
To hard boil an egg, we need elevated temperature.
But since water to use hard boiling has an unusually low temperature, it becomes more difficult since much of the water turns into vapor.
This is why at higher elevations, it takes a longer time to hard boil eggs.
