State Route 88 (SR 88), also known as the Carson Pass Highway, is a California State Highway that travels in an east–west direction, from Stockton, crossing the Sierra Nevada at Carson Pass, and ending at the border with Nevada, whereupon it becomes Nevada State Route 88, eventually terminating at U.S. Route 395.
Backfilling is the right one
Explanation:
It evaporates from the earth surface, condenses into clouds, and falls back to earth as rain or snow.
The disease has infected a few people, spread out over a large distance because Cholera can't suddenly spread, it infects few people and then spreads rapidly.