Explanation:

- We know the two numbers are in the ratio of 5:7.

- Let these numbers be 5x and 7x.

- The HCF (Highest Common Factor) is given as 3.

- Thus, x = 3.

- Hence, the numbers are 15 (5x = 5*3) and 21 (7x = 7*3).

- The LCM (Least Common Multiple) of two numbers is calculated using the formula: LCM × HCF = Product of the numbers.

- The product of the numbers is 15 * 21 = 315.

- Therefore, LCM = 315 / 3 = 105.

Correct Answer: Option 2: 105

- Option 1: 75 - Incorrect, doesn't satisfy calculations.

- Option 3: 125 - Incorrect, doesn't satisfy calculations.

- Option 4: 35 - Incorrect, doesn't satisfy calculations.

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