Which of the Following Statements Reflects the Concept of the Double

Which of the following statements reflects the concept of the double day?

A) A male-female couple can double the household's daily income if they both work outside the home.
B) Due to low wage employment, immigrants in Europe typically work two consecutive shifts in one day to support their families.
C) Women who work outside the home still perform the largest share of domestic work.
D) Through high-tech mechanization, European firms have been able to double their daily labor productivity.