In a mathematical model, the dependent variable is the outcome being explained or predicted, while independent variables are the factors influencing it. Here, the model explains “trips to the public neighborhood library” using variables like number of children, median income, median education, and distance. Thus, trips to the library (option C) is the dependent variable, as it is the outcome being modeled. The APA’sAICP Certification Exam Content Outline(2022), under “Research and Assessment Methods,” defines the dependent variable as “the outcome variable that the model seeks to explain, such as trips to a library in a travel demand model.” Options A, B, and D (number of children, distance, median education) are independent variables used to predict trips. TheCPC Study Manual(2024) confirms, “In a model explaining library trips, the number of trips is the dependent variable, while factors like distance and demographics are independent variables,” supporting option C.