The compound shown is 2,3,4-trichloropentane drawn without stereochemistry. Counting configurational isomers only, which of the following statements are correct?

C2 and C4 are ordinary stereocentres. C3 carries $\mathrm{H}$, $\mathrm{Cl}$ and two $\mathrm{CHClCH}{}_3$ groups that differ only in configuration, so C3 is a pseudoasymmetric centre. When C2 and C4 have opposite descriptors $(R,S)$ the two groups on C3 are enantiomeric and C3 has two distinct arrangements ($r$ and $s$); both of these molecules have a mirror plane through C3, giving 2 meso forms. When C2 and C4 have the same descriptor $(R,R)$ or $(S,S)$ the two groups on C3 are identical, so C3 is not a stereocentre and this gives one pair of enantiomers. Total $2+2=4$ stereoisomers.