What is Photochemical Reactions? And the factors affecting the Photochemical Reactions.

Question

$\begin{array}{1 1} \text{(a) A chemical reaction initiated by the absorption of energy in the form of light.} \\\text{(b) A chemical reaction initiated by decomposition caused by heat.}\\ \text{(c) A chemical reaction initiated by the absorption of energy in the form of heat and light.} \\ \text{(d)A chemical reaction initiated by the absorption of energy in the form of nuclear energy.}\end{array}$