An investigator finds a positive correlation between per capita alcohol consumption and mortality rates for breast cancer across 20 different countries. in order to investigate this relationship further, the investigators conduct a study selecting 200 women with breast cancer and comparing them with 200 women without breast cancer. the women are compared with respect to earlier drinking habits. if women with breast cancer are more likely than women without breast cancer to overestimate prior alcohol consumption, the apparent association between drinking and risk of breast cancer will be: a: decreasedb: unchangedc: altered, but the direction can not be predictedd: increased