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 option reflects a systematic approach to data collection (measuring multiple species under the same conditions) and incorporates research (journal articles) to support her findings, making her conclusions more robust and scientifically valid.