Choice A is the correct answer. Apply the doubling pattern.

1. Doubling periods: $\frac{27}{9} = 3$ periods.
2. After each doubling: Multiply by 2.
3. After 3 doublings: $3000 \times 2^3 = 3000 \times 8 = 24,000$.
4. Formula: $A(t) = 3000(2)^{t/9}$.

💡 Strategic Tip: 3 doublings = multiply by $2^3 = 8$.

Choice B is incorrect because this is after 2 doublings (18 years). Choice C is incorrect because this is after only 1 doubling (9 years). Choice D is incorrect because this is the wrong calculation.