Light intensity is? the distance between successive crests of a wave? the interference pattern that shows light is a wave? the rate at which a waves energy flows through a given unit of area? the direction that photons travel?

The correct answer is:
The rate at which a waves energy flows through a given unit of area

In fact, light intensity is defined as the light power per unit of area:

but the power is the energy carried by the light per unit of time:

this means that the intensity can be rewritten as

So, it's basically the rate of energy (per unit of time) through a given surface.

Answerwavelength;