From an Aeroplane just over a river, the angle of depression of two palm tree on the opposite bank of the river are found to be 60° and 30° respectively. If the breadth of the river is 400 m, then the height of the aeroplane above the river at that instant is :(Assume √3=1.732)

• A. 173.2 m
• B. 346.4 m
• C. 519.6 m
• D. 692.8 m