Final answer:
Evolution is called a scientific theory because it is well-supported by evidence and has been repeatedly tested and confirmed. It explains how species change over time and is widely accepted in the scientific community.
Step-by-step explanation:
Evolution is called a scientific theory because it is a well-substantiated explanation of how species change over time. As a scientific theory, it is supported by a large body of evidence from various scientific disciplines, including biology, genetics, paleontology, and geology. The theory of evolution has been repeatedly tested and confirmed through observation and experimentation, making it a credible and widely accepted explanation for the diversity of life on Earth.