A researcher has observed that people who suffer from an eating disorder tend to have lower self-esteem than people without a disorder. However, the researcher is not sure whether the lower...

A researcher has observed that people who suffer from an eating disorder tend to have lower self-esteem than people without a disorder. However, the researcher is not sure whether the lower self-esteem leads to an eating disorder or whether having an eating disorder leads to lower self-esteem. This is an example of

 a. the directionality problem.

b. the third-variable problem.

c. the extraneous variable problem.

d. the confounding variable problem.