Answer :
The answer is option c. f = 210,000 (0.5) t.
The rainforest is decreasing in size, so the rate of change is a fraction less than 1. Since each year the size is multiplied by a factor to get to the next year's size, that factor must be less than 1.
Of the above options, only answer choice (c) has a factor that is less than 1.
Choice (c) f = 210,000 (0.5) t. multiplies by 0.5 each year, which represents a 50% decrease.
Let's look at an example:
Year 1: 210,000 * 0.5 = 105,000 square miles
Year 2: 105,000 * 0.5 = 52,500 square miles
This demonstrates the continual decrease in size.
The answer is option c. f = 210,000(0.5)t