Mark (age 55 in 2020) and his late wife, Mary, were married in 1990. Mark and Mary have a son, Matt, who was born in 2009. Mary passed away on October 4, 2020. Mark has not remarried. Mark maintained a household for Matt, his dependent child ( qualifying child), for all of 2020 & 2021. What allowable filing status will be most beneficial for Mark to use in 2021?

a) MFJ

b) MFS

c) Head of Household

d) Qualifying Widow(er)

e) single