D.the sentence is correct as it is written
Answer:
Independent variable: Type of fertilizer
Dependent variable: Growth rate of carrots
Control variable: No fertilizer
Explanation:
An independent variable in statistics is defined as the variable that is manipulated, and a dependent variable is defined as the variable that is measured. A control variable is defined as a variable that doesn't change and is used to compare the other variables to. Furthermore, the independent and control variables are graphed on the <em>x</em>-axis, and the dependent variables are graphed on the <em>y</em>-axis.
In this case, the farmers <em>manipulate </em>the <em>type of fertilizer</em> they use to <em>measure </em>the <em>effect it has on growth</em>. The control variable would then be the carrots that grow without any fertilizer, because if the fertilizer does have an effect on growth, you would want to know how much or what kind of effect it has.
