Indicate Which One of the Following Sources Produces the Highest $\lambda$

Multiple Choice

Indicate which one of the following sources produces the highest energy photons.

A) a radio station with = 106.7 MHz
B) a dentist's x-ray source with $\lambda$ = 100 pm
C) the laser in a CD player with $\lambda$ = 650 nm
D) a microwave oven with 11eed61f_f4b7_55fa_a0ba_07ca7b78c11c_TB6562_11 = 6.0 11eed61f_f4b7_55fa_a0ba_07ca7b78c11c_TB6562_11 10¹⁰ Hz
E) your cell phone with 11eed61f_f4b7_55fa_a0ba_07ca7b78c11c_TB6562_11 = 1.750 GHz