A tower stands on the top of a building which is 40 metres high. The angles of depression of a point situated on the ground from the top and the bottom of the tower are found to be 60° and 45° respectively. What is the height (in metres) of the tower?

• A. 20√3
• B. 30(√3 + 1)
• C. 40(√3 - 1)
• D. 50(√3 - 1)