The best statement 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 response indicates that Ruby is measuring all species under the same controlled conditions, which is essential for a fair comparison of growth rates. Additionally, finding journal articles that provide scientific data adds credibility and external validation to her investigation.