A simple work mode choice model is estimated from data in a small urban area to determine the probabilities of individual travelers selecting various modes. The mode choices include auto-drive alone (DL), auto-shared ride (SR) and bus (B), and the utility functions are estimated as: UDL = 2.2 - 0.2 (costdL) - 0.03 (travel timepl) USR = 0.8 -0.2 (costsR) - 0.03 (travel times) UB = -0.2 (costb) - 0.01 (travel times) Where cost is in dollars and time is in minutes. Between a residential area and an industrial complex, 6000 workers depart for work during the peak hour. For all workers, the cost of driving an auto-drive alone (DL) is $ 6 with a travel time of 10 minutes the cost of driving an auto-shared ride (SR) is $ 3 with a travel time of 10 minutes. The bus fare is $1 with a travel time of 15 minutes. calculate the NMBER OF WRKERS USING DL mode. Select one: a. 3333 b. 4000 c. 5555 d. 6000