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 is systematically measuring the heights of multiple species under controlled conditions, which allows for a fair comparison of their growth rates. Additionally, finding journal articles offers further reliable evidence for her conclusions.