A lightning strike occurs 1.2km away from a student. The student sees the flash and then hears the thunder. If the flash and the thunder are produced simultaneously and the speed of sound in air is 340m/s, approximately how much later does the sound reach the student than the light?
(a) 0.0035s
(b) 7.1s
(c) 3.5s
(d) 0.40s