Step-by-step explanation:
The wave length is the length of the wave. One way to measure it is from the top of one wave to the top of the next. Here, the wave length is 1.0 m.
The frequency is the number of waves per second. We have 2 waves per 4 seconds, so the frequency is 2/4 = 0.5 Hz.
The amplitude is the distance from the center of the wave to the top or bottom. Here, the amplitude is 0.5 m.