Two progressive waves arrive at a stationary point $P$. The graph shows how the displacement of each wave at point $P$ changes with time. The two waves overlap at point $P$. What is the resultant displacement at time $0.38\,\text{s}$?
- A$+1.0\,\text{cm}$
- B$-1.0\,\text{cm}$
- C$+1.8\,\text{cm}$
- D$-1.8\,\text{cm}$