The rate of people entering a subway car on a particular day is modeled by the function R, where R(t) =0.038 - 0.8461 + 6.587t + 1.428 for 0≤t≤20. R(t) is measured in people per hour, and t is measured in hours since the subway began service for the day. Based on the model, at what value oft does the rate of people entering the subway car change from increasing to decreasing? A:T=20 B:T=17.056 C:T=13.295 D:T=5.505
