Which Example Illustrates the Thinking Error Known as Authority Fallacy

Which example illustrates the thinking error known as authority fallacy?

A) While shopping for a new bicycle helmet, you start with a popular brand, and you seek out positive reviews of that brand.
B) You change your beliefs about bicycle helmet laws in your state after hearing the opinion of an expert on the subject.
C) You believe a particular bicycle helmet must be worth buying because lots of professional cyclists wear it.
D) You decide it is safe to not wear a bicycle helmet while riding because your parents and grandparents never saw the need.