The number of different ways to colour the vertices of a square $PQRS$ using one or more colours from the set \{Red, Blue, Green, Yellow\}, such that no two adjacent vertices have the same colour is (A) 36 . (B) 48 . (C) 72 . (D) 84 .
The number of different ways to colour the vertices of a square $PQRS$ using one or more colours from the set \{Red, Blue, Green, Yellow\}, such that no two adjacent vertices have the same colour is\\
(A) 36 .\\
(B) 48 .\\
(C) 72 .\\
(D) 84 .