Final answer:
The town's population decreases by 10% each year as indicated by the expression showing exponential decay.
Step-by-step explanation:
The population of the town decreases by 10% each year. The expression 10,000(0.90)^t shows that the population is multiplied by 0.90 (or 90%) each year, which means that it retains 90% of the previous year's population, therefore losing 10% annually. This type of change is known as exponential decay.