A fast-food chain sells its burgers alone or as part of a "value meal" that includes fries and a drink. They know that some customers are health-conscious. They want to do an experiment to determine whether the proportion of customers choosing the meal would increase if they offered baby carrots with the meal as an alternative to fries. They will compare three treatments:

(1) status quo,

(2) offering carrots as an alternative but with no advertising, and

(3) offering carrots as an alternative and advertising this option in the local area. They have restaurants in three types of areas: cities, suburban areas, and along major highways.

a. Explain how they would conduct this experiment using a completely randomized design.

b. Explain how they would conduct this experiment using a randomized block design.

c. Explain why it makes sense to use the type of area in which a restaurant is located as a block determinant in this experiment.

d. Explain why a matched-pair design could not be used for this experiment.