Mason and his wife Madison had been married for five years. Jaxon, who is 15 years old and unrelated to Mason and Madison, has been living with Mason and Madison for the last two years. Last year (2020), Mason and Madison divorced. Mason and Jaxon stayed in the home and Madison moved out. During 2021, Mason provided all of Jaxon's support and Jaxon lived in the home for the entire year. Jaxon did not earn any income during 2021. What is Mason's filing status for 2021? (2 points)