Given $f(z) = \frac{1}{z+1} – \frac{2}{z+3}$. If $C$ is a counterclockwise path in the $z$-plane such that $\mid z+1 \mid =1$, the value of $\frac{1}{2 \pi \: j} \oint_c f(z) dz$ is
1. $-2$
2. $-1$
3. $1$
4. $2$