The Average Full-Time Working Woman Earns Less Than the Average

The average full-time working woman earns less than the average full-time working man in the United States. What is a common nondiscrimination explanation for this discrepancy?

A) Women customers prefer women employees, and women customers have less purchasing power overall.
B) Women are at a disadvantage in salary negotiations because they most often must negotiate against men.
C) Women are forced into less-demanding jobs because of the needs of childcare.
D) Women more often choose to work for smaller companies that have lower pay scales.