Consider the following differential equation:

$\dfrac{dy}{dt}=-5y$;    initial condition: $y=2$ at $t=0$.

The value of $y$ at $t=3$ is

1. $-5e^{-10}$
2. $2e^{-10}$
3. $2e^{-15}$
4. $-15e^{2}$