During $2021,$ it costs Sheffield, Inc. $\backslash (\backslash$$ $27\backslash )$ per unit to produce part T$5.$ During $2022,$ the unit cost has increased to $\backslash (\backslash$$ $30\backslash )$ per unit. In $2022,$ Southside Company has offered to provide Part T$5$ for $\backslash (\backslash$$ $10\backslash )$ per unit to Sheffield. No fixed costs are avoidable. Which of the following statements is true with regard to this make$-$or$-$buy decision?

Net relevant costs are $\backslash$$$17$ per unit.

Incremental revenues are $\backslash$$$3$ per unit.

Incremental costs are $\backslash$$$17$ per unit.

Differential costs are $\backslash (\backslash$$ $20\backslash )$ per unit.