Work, scientifically speaking, is done when a force is applied to an object which consequently moves the object at a certain direction. Work in formula, is force multiplied with distance.
W = F x d
Answer:
Frequency
Explanation:
Photons are the packet of energy. They are massless and chargeless particles. They travel in the vacuum with the speed of light. The energy of photon is given by :

Where
h = Planck's constant
= frequency of photon
Or 
c = speed of light
= wavelength of photon
From the above equation, it is clear that the energy of photon is directly proportional to its frequency.
Answer:
I'd love to help, but there isn't anything to choose from.
It can be measured by an ammeter.