Fred and Wilma are married taxpayers whose choose to file their federal income tax return using married filing joint status. They have three dependent children ages 2, 5, and 7 who live with them full-time. During 2018, Fred dies. Assuming Wilma does not remarry and the dependent children continue to live with her, what is her filing status during:

a) 2018 ___________________________

b) 2019 ____________________________

c) 2020 ___________________________

d) 2021 ___________________________