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: O U.S. farmers consider only their external costs in their decision making O U.S. farmers consider only their private costs in their decision making O the social cost of irrigation exceeds the social benefits. O Mexican farmers consider only their private costs in their decision making. If U.S.farmers were to internalize this externality, U.S. farmers would irrigate(Click to select) y las the (Click to select)