Electromagnetic spectrum — practice question

A beam of X-rays moving through air has wavelength $5.4 \times 10^{-10}\,\text{m}$. Calculate its frequency.

• A$5.6 \times 10^{-17}\,\text{Hz}$
• B$5.6 \times 10^{11}\,\text{Hz}$
• C$5.6 \times 10^{17}\,\text{Hz}$
• D$5.6 \times 10^{18}\,\text{Hz}$