Final answer:
The audience suspects Betty is feigning her illness because of the convenient timing of her symptoms and the lack of evidence supporting a true ailment.
Step-by-step explanation:
The audience suspects that Betty is most likely feigning her illness because there are hints within the context of the narrative that her condition is not genuine. For instance, Bernice's sudden claim of a headache, conveniently used to avoid social engagements, has no substantiation. Moreover, the lack of evolution in Betty's symptoms and her strategic timing in claiming illness when it serves her purpose indicate that her sickness may be a facade. In literature, such character actions suggest to the audience that there is a manipulation at play to gain sympathy or avoid certain situations.