What is the traditional meaning of a double workload?

What is the traditional meaning of a double workload?
 
  a. A condition associated with men and women in which one gender has to work two jobs to survive
  b. The condition under which a single, unmarried woman works two jobs to be able to afford her household
  c. A situation in which married women work both in outside employment and also within the home
  d. The condition under which a single female-headed household is supported solely by earnings of the mother herself
  e. A situation in which both the male and female in a household must be employed in order for the family to survive