A Study Compared Weight Loss in Obese Participants Between Those

A study compared weight loss in obese participants between those who participated in a support group and those who chose not to.Which of the following factors or conditions in the study would be considered an intervening variable?

A) Data collection for both groups occurred over the Thanksgiving holiday.
B) The group that did not participate in a support group had a greater percentage of male participants.
C) Three participants received a diagnosis of hypertension 1 month after the study began.
D) Two participants dropped out of the study 1 month after the study began.