A transverse progressive wave with wavelength $\lambda$ is formed on a stretched string. The graph illustrates how displacement $y$ changes with distance $x$ at one specific moment. At $x = \dfrac{\lambda}{8}$, the displacement is $y_1$. What are the next two values of $x$ for which the displacement $y$ once again has the value $y_1$?
- A$\dfrac{3\lambda}{8}$ and $\dfrac{5\lambda}{8}$
- B$\dfrac{3\lambda}{8}$ and $\dfrac{9\lambda}{8}$
- C$\dfrac{5\lambda}{8}$ and $\dfrac{9\lambda}{8}$
- D$\dfrac{9\lambda}{8}$ and $\dfrac{17\lambda}{8}$