Suppose a Treacherous Stretch of Road Winds Through Deadman's Canyon

Multiple Choice

Suppose a treacherous stretch of road winds through Deadman's Canyon for 5 miles.A highway department study estimates that better lighting would reduce the traffic fatality rates as follows: $$\begin{array} { c c c } \text { Number of lights } & \text { Estimated deaths per year } & \text { Total installation cost (in millions) } \\0 & 3 & \$ 0 \mathrm {~m} \\1 & 2 & \$ 3 \mathrm {~m} \\2 & 1.5 & \$ 7 \mathrm {~m} \\3 & 1.2 & \$ 12 \mathrm {~m} \\4 & 1 & \$ 18 \mathrm {~m} \\5 & 0.9 & \$ 25 \mathrm {~m}\end{array}$$
Suppose that experts have estimated the statistical value of a life saved to be $8m.The marginal benefit of the third light installed is ____ and the marginal cost is ____.Therefore the third light ____ be installed.

A) $2.4m;$5m;should not
B) $8m;$5m;should
C) $300,000;$5m;should not
D) $500,000;$1m;should not