$50.$ ?What type of taxpayer can claim a deduction for contributions to a self$-$employed retirement plan $($e$.$g$.,$ ?SEP$-$IRA or Solo $401($k$))$ ?during the year?

a$).$ ?Single individuals with no dependents.

b$).$ ?Married couples with no children.

c$).$ ?Single parents with one child.

d$.)$ ?Married couples with two children.