Atmospheric Pressure at Sea Level Is Equal 760 Mm Hg

Atmospheric pressure at sea level is equal 760 mm Hg.Denver,Colorado,is at an elevation of 5,280 feet above sea level,and so the atmospheric pressure in Denver is ~623 mmHg.Oxygen is found in the same percentage at both sea level and in Denver.What is the partial pressure of oxygen in Denver compared to at sea level?

A) The partial pressure of oxygen is higher in Denver than at sea level.
B) The partial pressure of oxygen is lower in Denver than at sea level.
C) The partial pressure of oxygen is the same in Denver as at sea level.