A simply supported beam of length $L$ is subjected to a varying distributed load $\sin(3\pi x/L) Nm^{-1}$ , where the distance $x$ is measured from the left support. The magnitude of the vertical reaction force in $N$ at the left support is
- $\text{zero}$
- $L/3\pi$
- $L/\pi$
- $2L/\pi$