Bridget started to fund a variable annuity. Three years later, she experienced financial difficulty. Sbe called her agent and cascelled the coetract. The inmurer returned all bet $4$ perceen of the account balance. The $4$ percest kept by the insurer is $a(n)$

A$)$ account administration fee.

B$)$ investment management fee.

C$)$ front$-$end load.

D$)$ surrender charge.