The best response that describes Ruby gathering enough evidence to support a scientific explanation concerning plant growth rates is:
"Ruby measures the heights of several species A, B, C, and D plants for a week under the same conditions and finds journal articles that describe the growth rates of each species."
This option indicates that Ruby has measured multiple species under controlled conditions, which allows for a valid comparison of growth rates, and she also seeks out reputable sources (journal articles) for additional evidence. This approach aligns with scientific methods for gathering and validating evidence.