Question

The diagrams show the sound waves produced in one second from various tuning forks.

Which sound wave has the lowest pitch?

An illustration of a tuning fork with lines parallel to the fork moving out. The lines start out farther apart, get closer together and then farther apart again.
An illustration of a tuning fork with lines parallel to the fork moving out. The lines start out farther apart, get closer together and then farther apart again. The line pattern then repeats.
An illustration of a tuning fork with lines parallel to the fork moving out. The lines start out close together, get farther apart and then close together again. The line pattern then repeats.
An illustration of a tuning fork with lines parallel to the fork moving out. The lines start out close together, get farther apart and then close together again. The line pattern then repeats. The farther apart section gets wider the further the lines are from the fork.

Answer 1

Lowest pitch = the diagram with the fewest wave cycles in one second — the first diagram (the one that shows only one bulge of wavefronts, not a repeating pattern).

Reason: pitch = frequency; fewer cycles per second = lower frequency = lower pitch.