Which of the Following Lasers Emits Photons with the Highest $\lambda$

Multiple Choice

Which of the following lasers emits photons with the highest frequency?

A) a Nd:YAG laser with $\lambda$ = 1064 nm
B) an Ar⁺ laser with $\lambda$ = 514.5 nm
C) a Kr⁺ laser with $\lambda$ = 647 nm
D) an ArF laser with $\lambda$ = 193 nm
E) a He-Ne laser with $\lambda$ = 633 nm