The Balances of Select Accounts of McMurray Company as of December

The balances of select accounts of McMurray Company as of December 31,2018 are given below: $$\begin{array} { | l | r | } \hline \text { Notes Payable-short-term } & \$ 1,500 \\\hline \text { Salaries Payable } & 3,000 \\\hline \text { Notes Payable-long-term } & 23,000 \\\hline \text { Accounts Payable } & 3,000 \\\hline \text { Unearned Revenue } & 3,000 \\\hline \text { Interest Payable } & 2,400 \\\hline\end{array}$$ The Unearned Revenue is the amount of cash received for services to be rendered in January 2019.Interest Payable will be paid on February 5,2019.What are the total long-term liabilities shown on the balance sheet at December 31,2018?

A) $1,500
B) $3,000
C) $6,000
D) $23,000