The hiker who feels the least pull of gravity from Earth would be the one at the highest altitude on the mountain. Since the question states that all four hikers have equal mass, the pull of gravity decreases as one moves farther away from the Earth's surface.
In a typical scenario, if we assume the picture shows the hikers at varying altitudes, the hiker at the highest point would feel the least pull of gravity. Based on this reasoning, if Callie is at the highest point in the picture, she would be the correct answer.
So the response would be:
Callie