The figure shows the high-frequency C-V curve of a MOS capacitor (at $T=300$K) with $Φ_{ms}=0 V$ and no oxide charges. The flat-band, inversion, and accumulation conditions are represented, respectively, by the points
1. $P,Q,R$
2. $Q,R,P$
3. $R,P,Q$
4. $Q,P,R$