HOW DO YOU DETERMINE THE CORRECT ANSWER?

Hi, we are asked if we have an O in 4, which could be 2 and 3. Our first rule tells us that if we have p and y next to each other they must be surrounded by R, so it is not possible that 2 and 3 are P and Y, so we can eliminate E. We can eliminate A since two oranges cannot be next to each other. We can eliminate B since O and R cannot be next to each other. Finally we can eliminate C since two purples cannot be next to each other