John and Jane Are a Married Couple Who Work as Independent

John and Jane are a married couple who work as independent consultants.Assume that John's average hourly fee is $80 and his marginal fee is $125 whereas Jane's average and marginal hourly fees are both $100.One of them can work on a short consulting assignment for $1,000.Which of the following is IRRELEVANT information to the decision for maximizing the family's income?

A) Jane's opportunity cost of doing other jobs
B) John's opportunity cost of spending more time with their kids
C) Jane's marginal cost
D) John's average cost
E) The number of hours spent on the assignment