Option C: G
To solve this problem, we need to determine the arrangement of colors on the cube's faces based on the given conditions. Let's analyze the information step by step:
     ● Condition 1: Colours Y, O, and B are on adjacent faces.  
     ● Condition 2: Colours I, G, and Y are on adjacent faces.  
     ● Condition 3: Colours B, G, and Y are on adjacent faces.  
     ● Condition 4: Colours O, V, and B are on adjacent faces.  
     From these conditions, we can deduce the following:
     ● Y is a common color in conditions 1, 2, and 3, indicating that Y is adjacent to O, B, I, and G.  
     ● B is a common color in conditions 1, 3, and 4, indicating that B is adjacent to Y, G, and O.  
     ● O is adjacent to Y and B (from condition 1) and V (from condition 4).  
     Since Y is adjacent to O, B, I, and G, it cannot be opposite to any of these colors. Therefore, Y must be opposite to V.
     Now, let's determine the face opposite to O:
         ○ O is adjacent to Y, B, and V.
         ○ Since Y is opposite to V, O cannot be opposite to V.
         ○ Therefore, the face opposite to O must be one of the remaining colors, which are I or G.
     Since G is adjacent to B and Y (from condition 3), and O is adjacent to B and Y (from condition 1), G cannot be adjacent to O. Thus, G must be opposite to O.
     Therefore, the color of the face opposite to the face colored with O is G.