An observer is positioned at the finishing line of a $100\ \text{m}$ race. He wants to measure the winner’s time. He begins his stop-watch as soon as he spots the smoke from the starting gun, rather than when he hears the bang. What is the reason for this?
- ALight travels much faster than sound.
- BThere is a risk he might respond to an echo from a wall.
- CHumans react slower to sound than to light.
- DHumans react more quickly to sound than to light.