3. The functions = f(t) gives the position of a body moving on a coordinate line, with s in meters and t in seconds. Find the body's displacement and average velocity for the given time interval. s=31+3t+10, 0 t2 A. 38 m, 19 m/sec B. 18 m, 9 m/sec C. 12 m, 15 m/sec D. 18 m, 18 m/sec