As per Rankine's theory of earth pressure, the inclination of failure planes is $\left ( 45 + \frac{\phi }{2} \right )^{\circ}$ with respect to the direction of the minor principal stress.

The above statement is correct for which one of the following options?

1. Only the active state and not the passive state
2. Only the passive state and not the active state
3. Both active as well as passive states
4. Neither active nor passive state

Answer: