Plants were grown in three mediums (A, B and C) and the height of the plant was measured after 4 weeks (cm). Data from 47 plants are recorded in the \textit{plantHeight} data frame. a) Perform an ANOVA test to determine if there is a significant difference between the plant heights between the three mediums. Does the medium they are grown in make a significant difference? (Clearly write up your test - state the hypotheses, significance level, reference the test results, state the decision and interpret it in a clear concluding statement.)