A van and a small car are traveling in the same direction on a twolane road. After the van passes the car, the driver of the car sounds his horn, frequency = 440 Hz, to signal the van that it is safe to return to the lane. (The van is still moving faster than the car.) Which is the correct statement?

(a) The car driver and van driver both hear the horn frequency as 440 Hz. 

(b) The car driver hears 440 Hz, but the van driver hears a lower frequency. 

(c) The car driver hears 440 Hz, but the van driver hears a higher frequency. 

(d) Both drivers hear the same frequency, and it is lower than 440 Hz.