At t=0s a crest on a stretched string is located at x=0.25m. At t=0.05s the same crest is observed at x=0.45m. Which statement about the wave’s propagation is correct?
a) It travels toward the −x direction
b) It travels toward the +x direction
c) The string sustains a standing wave, so no net propagation occurs
d) Its speed is 4m s−1, but the direction cannot be decided from the data