Single Adoptive Divorced parent - FAFSA Status

I don’t think I really have a choice - but it’s really not ‘correct,’ because after you choose ‘divorced,’ the next question is:

“What is the month and year your parents’ were married, separated, divorced or widowed?”

However, my ex-husband was not her parent. She does not have a second parent. So that line always throws me. Thanks for your guidance~