RBT Practice Exam 2025 – Comprehensive Exam Prep

The Y-axis usually represents the dependent variable or outcome variable in a graph. The dependent variable is the variable that is affected or influenced by the independent variable, which is usually shown on the X-axis. This is why options B, C, and D are incorrect. Option B mentions time, which can sometimes be shown on the Y-axis, but it ultimately depends on what is being graphed. Option C refers to a base condition, which is not typically represented on a graph. Option D mentions phase change, which is also not typically shown on a graph unless it is specifically measuring changes in phases.