Please help me with my ECONOMICS problem. I don't know how to answer it

Researcher A is interested in the wage differential between genders in the Brisbane area, She interviewed 4,520 full time employees in the Brisbane metropolitan area to collect data on weekly income and gender from each interviewee, along with other individual characteristics that may determine labour market outcomes. These include, but are not limited to, years of schooling, marital status, and number of kids. Every individual in the dataset is either male or female. Researcher Athen tried to regress Iog(income) on a dummy for male and a dummy for female, along with other characteristics including a constant. However, she was confused because STATA refused to compute the estimate for the dummy for male. In fact, STATA omits the dummy for male in order to avoid the problem known as: Hint: See page 23 to page 30 in Lecture Note 4. A 3- Omitted variable bias A [3- Perfect multicollinearity A c. Homoskedastic errors A d'Control variables