While observing all the three dice, we see that : From Figure 1 : 2 and 3 cannot be the opposite to 4. From Figure 2 : 1 and 3 cannot be the opposite to 4. From Figure 3 : 2 and 6 cannot be the opposite to 4. So, the remaining number 5 will be opposite to 4. Hence, the correct answer is "5".