Explanation:

- Prashant has invested the same amount, let's call it P, in both banks for 2 years.

- Bank A offers 20% per annum compound interest. The compound interest formula is: \( CI = P \times \left(1 + \frac{r}{100}\right)^n - P \).

- So, \( CI = P \times (1.2)^2 - P = P \times (1.44 - 1) = 0.44 \times P \).

- Bank B offers simple interest at r% per annum. The simple interest formula is: \( SI = \frac{P \times r \times t}{100} \).

- With t = 2 years, \( SI = \frac{P \times r \times 2}{100} \).

- Interest from Bank A is twice that from Bank B: \( 0.44 \times P = 2 \times \frac{P \times r \times 2}{100} \).

- Simplifying, \( 0.44 = \frac{4r}{100} \), \( r = 11 \).

- Correct Option: 3, which is 11%.