Water waves with wavelength $\lambda$ strike an obstacle at right angles and pass through a narrow opening. The opening has width equal to $\lambda$. The waves leaving the opening spread out through an angle $\theta$, as shown. The opening is then gradually made wider. Which changes, if any, happen to $\theta$ and to the wavelength of the waves that emerge?
- A$\theta$ decreases, wavelength remains the same
- B$\theta$ increases, wavelength remains the same
- C$\theta$ remains the same, wavelength decreases
- D$\theta$ remains the same, wavelength increases