Exponential Decay Initial Value Problem

The temperature of a cooling object is represented by a differentiable function $T$, where $T(t)$ is the temperature in degrees Celsius at time $t$ in minutes. The rate of change of the temperature is given by the differential equation $\frac{dT}{dt} = -kT$, where $k$ is a positive constant. At time $t=0$, the temperature is 180°C and is decreasing at a rate of 45°C per minute. Which of the following is an expression for $T(t)$?