Choice A is the correct answer. Solve for $r$ when $A = 3P$.

1. Equation: $3P = Pe^{20r}$.
2. Simplify: $3 = e^{20r}$.
3. Take natural log: $\ln(3) = 20r$.
4. Solve: $r = \frac{\ln(3)}{20} = \frac{1.0986}{20} \approx 0.055 = 5.5\%$.

💡 Strategic Tip: Use logarithms to solve for the exponent in exponential equations.

Choice B is incorrect because this rate would more than triple the investment. Choice C is incorrect because 15% is too high. Choice D is incorrect because 3% is too low to triple in 20 years.