A vehicle pulls out onto a single-lane highway that has a flow rate of 420 veh/hr (Poisson distributed). The driver of the vehicle does not look for oncoming traffic. Road conditions and vehicle speeds on the highway are such that it takes 1.7 seconds for an oncoming vehicle to stop once the brakes are applied. 

Which option below best represents the driver reaction times of oncoming vehicles so that the probability of an accident is 0.25? Assuming a negative exponential function of the headway.