Answer:
Biologists would explain the evolution of Musk oxen through the process called Natural Selection.
Step-by-step explanation:
Evolution through natural selection states that individuals who have specific characteristics that make them more fit to live in a particular environment are more likely to reproduce and generate offspring. When such advantages are hereditary, the offspring may acquire it, causing, over time, more individuals of that population to possess it, with consequent modification of the global characteristics of that species. From this perspective, less fit individuals tend to disappear, resulting in a better-adapted population.
Through this concept a biologist could explain how musk oxen evolved to possess warmest wool, assuming their ancestors had less warm wool. This was because most of the ancestors of the musk oxen had the less warm wool, however these animals lived in places where this wool was not efficient to ensure their survival, so they died over time. But some individuals who had the warmest wool survived and passed this feature on to their descendants.