What location on Earth experiences the least change in daylight hours as the seasons change and why?

The correct answer here is: The equator.

This is because the seasons are caused by a small tilt in the eaths axis: the Axis is not straight with respect to the movement around the sun, but it's tilted, pushing one pole (North or south) closer or away from the Sun.

This tilt affects the pole region the most and the equator region the least. At the poles the tilt causes extreme variations in the lenght of daylight hours: from perpetual daylight for days to no daylight for days.

The effect is strongest at the poles and weakest far away from the poles: at the equator.