The function r(t) is the rate of change of the quantity of water in a county reservoir, in acre-feet per day. an acre-foot is a volume of water that would cover one acre of land to a depth of 1 foot, and t is the number of days since the beginning of the year. interpret the definite integral r(t)dt what are the correct units of the definite integral? o the definite integral represents the average rate of change in the volume of water in the reservoir between t 30 and t60. the units of the given definite integral are acre-feet per day. the definite integral represents the total change in the volume of water in the reservoir between t 30 and t 60 the units of the given definite integral are acre-feet. andt 60. the units of the given definite integral are acre-feet per day. t 30 and t 60. the units of the given definite integral are acre-feet per day. o the definite integral represents the total change in the volume of water in the reservoir between t 30 o the definite integral represents the rate of change in the volume of water in the reservoir between the definite integral represents the total volume of water in the reservoir when t-60. the units of the given definite integral are acre-feet.