The phase of the Moon that produces the least variation in tides on Earth is B. third quarter moon.
During the third quarter and the first quarter phases, the Sun and Moon are at right angles to each other relative to the Earth, resulting in what is called "neap tides." Neap tides have the least difference between high and low tides, whereas full moons and new moons lead to "spring tides," where the difference is greater. Although gibbous and crescent moon phases occur between these phases, the third quarter specifically is one of the times of minimal tidal variation.