A Study Recruited 48 Overweight Adults Aged 55 to 75

A study recruited 48 overweight adults aged 55 to 75 years, and randomly divided them into two groups. Participants in one group drank 2 cups of water prior to their meals; the other group did not. All participants ate a low-calorie diet during the study. Over the course of 12 weeks, water drinkers lost about 15.5 pounds, while the non-water drinkers lost about 11 pounds, on average.
Here is a quote from the published study: "Due to an unintended greater random allocation of men to the water group than the non-water group, additional analyses were performed to determine if weight loss outcomes differed between men and women in the two groups." Based on this study, which of the following is true?

A) Gender is a confounding variable.
B) Gender is the response variable.
C) The study is biased in favor of men.
D) All participants should have been male.