That light has a dual nature is referring to light: having energy and momentum. having high- or low-energy photons. acting as waves and particles. undergoing pair production.

Option C, acting as waves and particles

Explanation:

Light has dual nature  because it acts both as a wave and particle. It has high energy particle i.e photons and it also behave as an electromagnetic wave. This property of light is studied under the quantum mechanics. Einstein also proved that light is a stream of photons possessing both electrical and magnetic properties.

Hence, option C is correct

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.