Horse's reproduce using two parents. Horse's became larger over time. Smaller Horse's went extinct, and then larger Horse's formed. Smaller Horse's are better suited to the environment than larger Horse's.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A geologist found fossils of horse bones in different rock layers of a canyon. The fossils in the lower levels show shorter bones than those in the upper-level fossils. Which conclusion is based on the geologist's observations?
Possibilities:
- Horse's reproduce using two parents.
- Horse's became larger over time.
- Smaller Horse's went extinct, and then larger Horse's formed.
- Smaller Horse's are better suited to the environment than larger Horse's.

Horse's became larger over time.