Correct Answer - Option 3 : 27

**Given:**

The product of two numbers is 243

Their LCM is thrice of their HCF

**Formula used:**

Product of two numbers = HCF × LCM

**Calculation:**

Let the HCF be x and LCM be 3x

Now, from the formula, we can write, 3x × x = 243

⇒ 3x^{2} = 243

⇒ x^{2} = 81

⇒ x = 9

⇒ 3x = 27

**∴ The LCM of the two numbers is 27.**