Choice A is the correct answer. Apply monthly compounding to the loan.

1. Values: $P = 20000$, $r = 0.09$, $n = 12$, $t = 5$.
2. Formula: $A = 20000(1 + \frac{0.09}{12})^{60} = 20000(1.0075)^{60}$.
3. Calculate: $(1.0075)^{60} \approx 1.57117$, so $A \approx 31,423.48$.

💡 Strategic Tip: Monthly rate = $\frac{0.09}{12} = 0.0075$, number of periods = $5 \times 12 = 60$.

Choice B is incorrect because this assumes simple interest. Choice C is incorrect because this uses quarterly compounding. Choice D is incorrect because the calculation is wrong.