The following four questions appeared in a survey. Which of the questions is(are) a contingency ...

The following four questions appeared in a survey. Which of the questions is(are) a contingency question? Q1: Are you married? (Yes, No) Q2: How old was your spouse on his/her last birthday? Q3: What is your spouse's current employment status? Q4: What is your current employment status?
 
  a. Q1 is a contingency question and the rest are not.
  b. Q1, Q2, and Q3 are contingency questions and Q4 is not.
  c. Q2 and Q3 are contingency questions and Q1 and Q4 are not.
  d. Q2, Q3, and Q4 are contingency questions and Q1 is not.
  e. All four questions are contingency questions.