A soil sample is subjected to a hydrostatic pressure, $\sigma$. The Mohr circle for any point in the soil sample would be

1. a circle of radius $\sigma$ and center at the origin
2. a circle of radius $\sigma$ and center at a distance $\sigma$ from the origin
3. a point at a distance $\sigma$ from the origin
4. a circle of diameter $\sigma$ and center at the origin