Exponential Growth Model

Let $A(t)$ be the amount of money, in thousands of dollars, in an investment account at time $t$ years. The function $A$ is differentiable and satisfies the differential equation $\frac{dA}{dt} = kA$, where $k$ is a constant. At time $t=0$, the account balance is 320 thousand dollars and is increasing at a rate of 80 thousand dollars per year. Which of the following is an expression for $A(t)$?