The angle of depression of two points A and B on a plane field from the top of a mast erected between A and B are 30° and 45° respectively. If A is westward of B, find |AB| if the height of the mast is 15m from the field.

• A.15√3m
• B.5(3 + √3)m
• C.15(1 + √3)m
• D.15(√3 - 1)m