For the following independent situations, determine the filing status for the years in question (all individuals are U.S. citizens). 

a. Wayne and Celia had been married for 24 years before Wayne died in an accident in 2020. Celia and her son, Wally, age 21 in 2020, continued to live at home through 2023. Wally worked part-time (earning $5,000 each year) and attended the university on a part-time basis. Celia provided more than 50% of Wally’s support for all four years. What is Celia’s filing status for 2020, 2021, 2022, and 2023?
b. Juanita is an unmarried parent who maintained a household for her unmarried son Josh, age 19. Josh worked full-time and earned $16,000. Juanita provided approximately 40% of Josh’s support but provided all the expenses of maintaining the household. What is Juanita’s filing status?
c. Gomer and Gertrude are married and have one dependent son. In April, Gomer left Gertrude a note informing her that he needed his freedom and he was leaving her. As of December, Gertrude had not seen nor heard a word from Gomer since April. Gertrude fully supported her son and completely maintained the household. What is Gertrude’s filing status assuming she was still legally married?