Sound travels through air at $330\,\text{m s}^{-1}$. Which size of architectural features in a large concert hall would produce the best diffraction of sound waves with frequency $0.44\,\text{kHz}$?
- A$1.3\,\text{mm}$
- B$750\,\text{mm}$
- C$7.5\,\text{m}$
- D$17\,\text{m}$