RESEARCH STUDY 9.2: Dr. Finkel is a social psychologist who studies romantic relationships. Several researchers have found that there is a link between income and marital satisfaction (e. g., Dakin & Wampler, 2012). Dr. Finkel is curious as to whether there is a causal link between the two variables, such that having a higher income causes higher levels of marital satisfaction. He is confident that he cannot reasonably or ethically manipulate people's income level, so he decides to use a multivariate design. He is also curious as to whether there is a causal link between these two variables or if two other variables (number of arguments and life satisfaction) can explain the relationship. He measures his three variables in a sample of 124 married couples recruited from a local community center. Below are his results. DV: Marital Satisfaction
Variable Beta (β) Significance (rho)
Income .69; .03
Number of arguments −.73; .01
Life satisfaction .13; .81

Which of the following can be concluded based on the results of Dr. Finkel's study?
a. Income is a stronger predictor of martial satisfaction than either the number of arguments or life satisfaction.
b. As the number of arguments a couple has increases, their marital satisfaction increases as well, controlling for income but not life satisfaction.
c. The beta for the relationship between life satisfaction and marital satisfaction is significantly different than zero.
d. The relationship between life satisfaction and marital satisfaction has the weakest effect size of all of the results.