To test the effects of a new fertilizer, 100 plots were divided in half. fertilizer a is randomly applied to one half, and b to the other. this is ;
(a) an observational study.
(b) a matched pairs experiment.
(c) a completely randomized experiment.
(d) a block design, but not a matched pairs experiment.
(e) impossible to classify unless more details of the study are provided

(b) a matched pairs experiment.

Explanation:

A match pair design or experiment is a randomized experimental procedure. It can be used in the experiment with two different sets of conditions and the subjects can be grouped into pairs. It is based on some of the blocking variable. The subjects are randomly assigned to different treatments.  

The given situation is an example of a matched pair experiment. This is because of the fact that there are two sets of conditions that is the use of fertilizer A and fertilizer B on different halves of the plot randomly to determine their effects.

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