In Which of the Following Scenarios Is a Paired Design

Multiple Choice

In which of the following scenarios is a paired design not appropriate?

A) Comparison of the wear pattern on one's left shoe and one's right shoe.
B) Comparison of a cream and an ointment in the treatment of a rash, where the ointment is applied to half the rash and the cream to the other half.
C) Comparison of the average energy use of two brands of dishwashers.
D) Comparison of the accuracy of taking a person's temperature orally and in the ear, where each person's temperature is taken using both methods.