In order to determine which type of data is presented on the y-axis of the scatter plot, it is necessary to view the plot itself. However, based on the context and the options provided, if the scatter plot is comparing "age" and "credit card debt," it is likely that the y-axis represents one of those two variables.
Typically, in a scatter plot, the independent variable (often thought of as the cause) is placed on the x-axis, while the dependent variable (often thought of as the effect) is placed on the y-axis. If credit card debt is being measured as it relates to age, then the y-axis would likely represent "credit card debt."
Without visual confirmation, the answer may depend on your understanding of the variables in the scatter plot. If the commonly understood relationship is true, the likely answer could be credit card debt.