Explanation:

- The market price of rice and wheat is originally in the ratio 3:2.

- Monthly expenses for rice and wheat are in the ratio 5:6.

- When the price ratio changes to 4:3, expenses need to be recalculated.

- Assume the amount bought remains the same.

- If P is the price per kg and Q is the quantity:

- Original expense for rice = 3P * Q = 3PQ.

- Original expense for wheat = 2P * (Q / 3 * 6/5) = 4PQ.

- New expenses:

- New price for rice = 4P/3.

- New price for wheat = 3P/2.

- New expense ratio: (4P/3 * Q) / (3P/2 * (Q/3 * 6/5)).

- Calculate and simplify new ratio:

- Ratio = 20 : 27.

- Correct option is 20 : 27.

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