Question

Use the graph to answer the question.
(Graph showing body mass of horse slowly rising over millions of years)
Select two statements that would best explain the change in horses’ body mass over millions of years.
(1 point)
Horses with larger body masses were less likely to survive and reproduce.
There was decreased food availability.
There was increased food availability.
Horses with larger body masses were more likely to survive and reproduce.
Large body mass occurred in individuals as they became adult

Answer 1

Correct choices: "There was increased food availability." and "Horses with larger body masses were more likely to survive and reproduce."

Explanation: Over millions of years an increase in average body mass is best explained by natural selection favoring larger individuals (they survived and reproduced more) and by environmental conditions (more food) that allowed larger size to be sustained. Individual growth to adulthood does not explain a long-term shift in population averages.