Which of the following statements are $CORRECT$?

1. For a rheopectic fluid, the apparent viscosity increase with time under a constant applied shear stress
2. For a pseudoplastic fluid, the apparent viscosity decreases with time under a constant applied shear stress
3. For a Bingham plastic, the apparent viscosity increases exponentially with the deformation rate
4. For a dilatant fluid, the apparent viscosity increase with increasing deformation rate
1. $P$ and $Q$ only
2. $Q$ and $R$ only
3. $R$ and $S$ only
4. $P$ and $S$ only