A loudspeaker is placed 2m in front of a long, vertical wall. A microphone is positioned 4m to the right of the loudspeaker and also 2m in front of the wall. What is the approximate extra distance travelled by the sound that reaches the microphone after reflecting once from the wall compared with the direct sound?
(a) 5.7m
(b) 1.7m
(c) 0.0m
(d) 2.0m