The following statements are given: (P) Conformational isomers are interconvertible by rotation around a single bond while configurational isomers cannot be interconverted without breaking a bond. (Q) Configurational isomers could be optically active or optically inactive while conformational isomers are optically inactive. (R) Geometric isomers must have a double bond in their structures. (S) Geometric and optical isomers are the two distinct categories of configurational isomers. Choose the correct combination of statements.