Choice A is the correct answer. Find the decay factor and convert to a rate.

1. Decay Factor: $b = \frac{24,000}{30,000} = 0.8$.
2. Verify: $\frac{19,200}{24,000} = 0.8$ (consistent).
3. Depreciation Rate: $r = 1 - b = 1 - 0.8 = 0.2 = 20\%$.

💡 Strategic Tip: Depreciation rate = $1 - \text{(decay factor)}$. If the value keeps 80%, it loses 20%.

Choice B is incorrect because 80% is the retention rate (what remains), not the depreciation rate. Choice C is incorrect because this is the dollar amount lost in year 1, not the percentage rate. Choice D is incorrect because this doesn't match the pattern in the table.