In the United States, the volume of irrigation water is usually expressed in acre-feet. One acre-foot is a volume of water sufficient to cover 1 acre of land to a depth of 1 ft (640 acres = 1 mi² ; 1 mi = 5280 ft).  The principal lake in the California Water Project is Lake Oroville, whose water storage capacity is listed as 3.54 x 10⁶ acre-feet. Express the volume of Lake Oroville in 

(a) Cubic feet; 

(b) Cubic meters; 

(c) U.S. gallons.