Industrial melanism observed in different species of moths is an...

Industrial melanism is a classic example of directional selection.

Before industrialization, light-coloured moths were more prevalent because they were well-camouflaged against the lichen-covered tree trunks, protecting them from predators. However, during industrialization, pollution killed the lichens and darkened the tree trunks with soot. This environmental change favoured the dark-coloured (melanic) moths, which were now better camouflaged. As a result, the population shifted in one specific direction towards the darker phenotype.

This shift in the frequency of a trait in a consistent direction in response to environmental changes is the defining characteristic of directional selection.

Answer: directional selection