Which of the following individuals is NOT considered a qualifying person for the head of household status when the taxpayer is legally unmarried $($single$)?$ a$)$ A child $5-$year$-$old child of the taxpayer who lives in the home all year b$)$ A brother of the taxpayer who lives in the home $9$ months who has no income and was fully supported by the taxpayer c$)$ A parent living in an assisted living facility who has $$20,000$ of non$-$taxable social security income and was supported $($more than half$)$ by the taxpayer d$)$ A friend living with the taxpayer the entire year who has no income and was fully supported by the taxpayer