It’s B. Substitution hope this helps
Frequency = speed of light
---------------------------
wavelength
= 3 x 10^8
------------------------
344 x 10^-9
= 8.72 x 10^14 Hz.
Hope this helps!
The potential energy ..
1- when a rubber band is stretche and waiting to be released
2- an acorn hanging from a oak tree
3- a pice of celery