Which phenomenon best describes a lunar eclipse?

A lunar eclipse occurs when the Earth passes directly between the Sun and the Moon, causing the Earth's shadow to fall on the Moon. This alignment can only happen during a full moon, when the Sun, Earth, and Moon are nearly in a straight line. During the event, the Earth obstructs the sunlight that would normally illuminate the Moon, resulting in the Moon appearing darkened or even taking on a reddish hue, known as a "blood moon," due to the refraction of light through the Earth's atmosphere.

The other options describe different celestial arrangements. The scenario where the Moon is between the Earth and the Sun describes a solar eclipse, not a lunar eclipse. The statement about the Sun being behind the Earth represents a situation that may not necessarily relate directly to an eclipse phenomenon but rather the general arrangement of celestial bodies. The Moon reflecting sunlight is a constant characteristic of the Moon but does not pertain directly to the event of a lunar eclipse itself. Therefore, the most accurate description of a lunar eclipse is when the Earth is positioned between the Sun and the Moon.