Question

Tidal ranges will be greatest when the earth and the moon are at

Answer 1

Tidal ranges will be greatest when the Earth and the Moon are at their closest distance. 
The Moon with it's gravitational field, pulling force, causes the water on Earth to rise, on the part faced towards the Moon, and to retreat, on the part of the Earth that is not faced towards the Moon. The closer the Earth and the Moon are, the bigger the influence from the Moon and the Earth's surface waters, thus the bigger the tidal range.