Explanation:

Let's calculate the difference in compound interest when compounded yearly and half-yearly:

- Compounded Yearly:

- Principal = Rs 12,000

- Rate = 20%

- Time = 1.5 years (18 months)

- CI = P(1 + r)^t = 12,000(1 + 0.20)^1.5 = Rs 13,866

- Compounded Half-Yearly:

- Principal = Rs 12,000

- Rate per half-year = 10% (half of 20%)

- Number of periods = 3 (each half-year)

- CI = P(1 + r/n)^(nt) = 12,000(1 + 0.10)^3 = Rs 13,998

- Difference: Rs 13,998 - Rs 13,866 = Rs 132

- Correct Option: Option: 2 - 132