The correct answer is $\boxed{\text{B}}$.
The distance between two meridians decreases as you move away from the equator. This is because the Earth is not a perfect sphere, but is instead slightly wider at the equator than it is from pole to pole. The Earth’s circumference at the equator is 40,075 kilometers, while its circumference from pole to pole is 40,008 kilometers. This means that the Earth’s radius at the equator is 6,378 kilometers, while its radius from pole to pole is 6,356 kilometers.
As a result of the Earth’s shape, the distance between two meridians decreases as you move away from the equator. At 60 degrees latitude, the distance between two meridians is 860 kilometers. This is about 86% of the distance between two meridians at the equator.
Option A is incorrect because it is the distance between two meridians at the equator. Option C is incorrect because it is the distance between two meridians at 30 degrees latitude. Option D is incorrect because it is the distance between two meridians at 45 degrees latitude.