Final Answer:
When a novel trait evolves in a population and contributes to speciation, it is referred to as a "Derived characteristic." Option A) is the answer.
Step-by-step explanation:
Derived characteristics, also known as evolutionary novelties or apomorphies, are traits that have evolved in a particular lineage and distinguish it from its ancestors. These traits can play a crucial role in the process of speciation, contributing to the formation of distinct species. Adaptive radiation (Option B) involves the rapid diversification of a common ancestor into various ecological niches. Hybrid infertility traits (Option D) and temporally isolated traits (Option C) are not specifically associated with the evolution of novel traits leading to speciation.
Option A (Derived characteristics) is the answer.