Answer:
The corrrect answer will be option-A.
Step-by-step explanation:
A scientific experiment contains two types of groups: the control and the experimental groups. The control group in any scientific experiment is the sample which does not receive the variable we need to test which is provided in the experimental groups.
In the given question, the scientist wanted to study the effect of fertilizers on the growth of the grass. so the parameter (variable) to be studied is fertilizer. The experimental samples are provided with different concentration of the fertilizer but the control sample will not receive the fertilizers as the control sample provides the base or reference to the experimental group to increase the accuracy of the results obtained.
Thus, option-A is the correct answer.