A student formulated a hypothesis that cotton will grow larger bolls (node) if magnesium is added to added to the soil. The student has two experimental fields of cotton, one with mannesium and one without. Which data should be collected to support this hypothesis?
(a) height of the cotton plants in both fields
(b) diameter of the cotton bolls in both fields
(c) length of the growing season in both fields
(d) color of the cotton bolls in both fields Why?

According to the hypothesis, the application of magnesium to cotton plants would support the growth of large cotton bolls. The field without magnesium would serve as control here. Cotton bolls from both the fields should be collected and their diameter should be measured.

If the diameter of the cotton bolls from the field with magnesium application is more than that of the cotton bolls from the control field with no magnesium, the hypothesis is correct. Therefore, measurement and comparison of the diameter of cotton bolls from the experimental and control field would allow the student to check the hypothesis.