Question

we would observe a totally dark moon starting to become illuminated when the moon moves between which two phases?
position w and position z
position z and position y
position y and position x
position x and position w

Explanation:

When the moon is in the new - moon phase (totally dark), it starts to become illuminated as it moves towards the waxing crescent phase. In the lunar cycle, the new - moon is followed by the waxing crescent. If we assume Position Y is the new - moon (totally dark) and Position X is the waxing crescent (starting to be illuminated), this matches the described phenomenon.

Answer:

Position Y and Position X