All of the following Vermont residents have reported taxable social security on their federal tax returns. Which of them may qualify to subtract 100% of their federally taxable social security income from their Vermont return?

Karl will file head of household and has Vermont adjusted gross income of $52,000.

Sarah is single and has Vermont adjusted gross income of $47,000.

Kevin and Rebecca will file a joint return and have Vermont adjusted gross income of $71,400.

William and Stephanie will file a joint return and have federal adjusted gross income of $59,400.