Asociologist wants to study popular attitudes and perceptions about astrology among college students in california. she believes that people who have astrological signs identified with fire will have a greater knowledge of astrology because fire signs tend to have more interesting and attractive symbolism. what are the variables in this study?

I believe the answer is: astrological signs and knowledge of astrology

Variables refers to the factors that might influence the conclusion of  a certain study. In the study above,  popular attitudes and perceptions is what we considered as the dependent variables (which is influenced by other variables). While astrological signs and knowledge of astrology is what considered as independent variables (which is used to measure the dependent variable)