When U. S. farmers in the Southwest irrigate their land, salt in the ground soil leaks into the Colorado River. The Colorado River has become so salty that Mexican farmers further down the river cannot irrigate their own land and Mexican crops have been devastated. This situation constitutes a negative externality because: a. U. S. farmers consider only their external costs in their decision making.
b. Mexican farmers consider only their private costs in their decision making.
c. U. S. farmers consider only their private costs in their decision making.
d. The social cost of irrigation exceeds the social benefits.

Since opening night, attendance at play a has increased steadily, while attendance at play b first rose and then fell. equations modeling the daily attendance y at each play are shown below, where x is the number of days since opening night. on what day(s) was the attendance the same at both plays? what was the attendance? play a: y = 8x + 191 play b: y = -x^2 + 26x + 126 a. the attendance was never the same at both plays. b. the attendance was the same on day 5. the attendance was 231 at both plays on that day. c. the attendance was the same on day 13. the attendance was 295 at both plays on that day. d. the attendance was the same on days 5 and 13. the attendance at both plays on those days was 231 and 295 respectively.