A do-nothing and two mutually exclusive alternatives are being considered for reducing traffic congestion. User benefits come from reduced congestion once the project is complete, while user disbenefits are due to increased congestion during construction. The interest rate is 8%, and the life of each alternative is 15 years. Assume these numbers apply to a private firm and use a present worth index to decide which alternative should be chosen. (You are required to write LaTeX: \frac{\Delta B}{\Delta C} B C ratio. If you choose do-nothing alternative, write 0 in the blank)A B User benefits ($M/yr) 2.1 2.6 User disbenefits ($M) 1.2 2.1 First cost ($M) 6.9 9.9 Op & maint.($M/yr) 0.75 0.825