The following table provides phenotypic data for a population of mammoths living in cold environments based on fossil and DNA evidence.
Characteristic Percent of Population Showing Trait by Generation
Generation 1 Generation 2 Generation 3
Tusks greater than 2.5 m in length 25 25 25
Tusks less than 2.5 m in length 75 75 75
Mass greater than 4,000 kg 15 15 15
Mass less than 4,000 kg 85 85 85
Fur thickness greater than 6 cm 15 25 35
Fur thickness less than 6 cm 85 75 65
Based on this data and your knowledge of natural selection, which explanation best explains the trends seen in the data?
(1 point)