Geena is testing an ad using the nine principles established by positioning advertising copy testing (pact). when she isolates mall intercept participants and does not disclose what the interviews are about, she is trying to adhere to the seventh principle, which is to

a. develop a consumer response model.
b. provide controls to avoid the biasing effects of the exposure context.
c. establish communication objectives.
d. decide whether to use pretests or posttests.
e. create a model that uses multiple measures.

B) provide controls to avoid the biasing effects of the exposure context.

Explanation:

The Positioning Advertising Copy Testing (PACT) are a set of 9 principles used to test the effectiveness of advertisements. They were developed by a group of 21 leading advertising agencies.

Provides measurements which are relevant to the objectives of the advertising. Requires agreement about how the results will be used in advance of each specific test. Provides multiple measurements, because single measurements are generally inadequate to assess the performance of an advertisement. Based on a model of human response to communications—the reception of a stimulus, the comprehension of the stimulus, and the response to the stimulus. Allows for consideration of whether the advertising stimulus should be exposed more than once. Recognizes that the more finished a piece of copy is, the more soundly it can be evaluated and requires, as a minimum, that alternative executions be tested in the same degree of finish. Provides controls to avoid the biasing effects of the exposure context.: it refers to how the audience recalls the ads depending on whether they were TV, radio or printed ads.Takes into account basic considerations of sample definition. Demonstrates reliability and validity.