A water wave travels through an opening in a harbour wall and undergoes diffraction. The opening is $8\,\text{m}$ across. The wave moves directly towards the opening. For which wavelength is the diffraction of the wave the greatest?
- A$1\,\text{m}$
- B$2\,\text{m}$
- C$4\,\text{m}$
- D$8\,\text{m}$