Answer
See the graph below.
Work Step by Step
The given snapshot is at $t=2$ s, and the wave moves to the left at 1 m/s.
This means that, after 1 s, the leading edge will be at $x=0$, and after 3 s, the middle point between the two parts of the wave (upper part and lower part) will be at $x=0$. Noting that the wave is 4 m wide.
Hence, the trailing edge will reach $x=0$ s after 5 s since the lower part width is 2 meters.
And since we start at $t=2$ s, so
At $t=3$ s, the leading edge reaches $x=0$,
At $t=5$ s, the middle point reaches $x=0$,
At $t=7$ s, the trailing edge reaches $x=0$,
Hence, the history graph is seen below.
