A Psychologist Notes That There Is a Correlation Between Physical

A psychologist notes that there is a correlation between physical health and the number of vacations that a person takes.People who take more vacations tend to have better physical health.After thinking about this result,you realize that this association may be due to a third factor: income.People with more income can afford more vacations and can afford better health care.Your explanation for this is most consistent with which limitation of correlational research?

A) the bidirectional causality problem
B) the third variable problem
C) the placebo effect
D) experimenter expectancy effects