Explanation:

- To find the initial sum, we use the formula for compound interest: \( A = P(1 + r)^n \), where \( A \) is the amount, \( P \) is the principal, \( r \) is the rate, and \( n \) is the number of years.

- Given:

- After 2 years, the amount is Rs10,890.

- After 3 years, the amount is Rs11,979.

- Using the relationship between the two amounts for year 2 and year 3:

- $$ \frac{11979}{10890} = (1 + r) $$

- $$ 1 + r = \frac{11979}{10890} \approx 1.10 $$

- By finding the principal:

- For 3 years: \( 11979 = P \times (1.10)^3 \)

- Calculating \( P \) gives us approximately Rs9,000.

- The correct option is Option 1, Rs9,000.