**Concept:** **The question tests on Age problem**

**Solution:**

Let Tom's age = x

Then Nicks age = 3x

Harry's age = 2 * 3x = 6x

Average age of all 3 = (x + 3x + 6x)/3 = 10x/3

Nicks age is 1 year less than the average age, i.e 3x = 10x/3 - 1

9x = 10x - 3

x = 3

Harry's age = 6x = 6 *3 = 18**Option B**