The diagram represents a rectangular block with dimensions $x$, $2x$ and $3x$. Electrical contact may be established with the block across opposite pairs of faces (for example, across the faces labelled R). Which statement about the electrical resistance of the block is correct?
- AIt is maximum between the faces labelled P.
- BIt is maximum between the faces labelled Q.
- CIt is maximum between the faces labelled R.
- DIt is the same, whichever pair of faces is used.