Why are lightning arresters placed at the apex of the structures ?

Question

$\begin{array}{1 1} (a)\;\text{because lightning tends to strike the highest object in the vicinity} \\ (b)\; \text{it acts as a conducting path of charge for high potential to zero potential} \\ (c)\; \text{because they form the easiest path to ground} \\ (d)\; \text{all the above}\end{array}$