Correct Answer - C
We have `P^(3)=Q^(3)` and `P^(2)Q=PQ^(2)`
Subtracting, we get
`P^(3)-P^(2)Q=Q^(3)-Q^(2)P`
`P^(2) (P-Q)+Q^(2) (P-Q)=O`
`(P^(2)+Q^(2)) (P-Q)=O`
If `|P^(2)+Q^(2)|ne O` then `P^(2)+Q^(2)` is invertible
`implies P-Q=O` (contradiction)
Hence `|P^(2)+Q^(2)|=0`