Which of the Following Marketing Applications Is Not an Example

Which of the following marketing applications is not an example of trace analysis?

A) The age and condition of cars in a parking lot were used to assess the affluence of customers.
B) A sample of 100 magazines were examined to determine how the portrayal of women in U.S. magazine advertisements has changed over the past 10 years.
C) The selective erosion of tiles in a museum indexed by the replacement rate was used to determine the relative popularity of exhibits.
D) The magazines people donated to charity were used to determine people's favorite magazines.