If the average product of labor is equal to $10$ units when $5$ units of labor are used, then total product of labor is equal to

Choice $1$ of $5$:A$.2$ units.

Choice $2$ of $5$:B$.5$ units.

Choice $3$ of $5$:C$.10$ units.

Choice $4$ of $5$:D$.50$ units.

Choice $5$ of $5$:E$.$ None of the above