from 0 years to 1 year:
91-70 = 21
21 / 91 = 0.23 = 23%
From 1 year to 2 years:
70-54 = 16
16 / 54 = 0.29 = 29%
because the percentages are different, it isn't linear. This would be an exponential equation.
The answer is C. because you would multiply the starting population (91) by a percentage of decline raised tot he power of the number of years, as shown in the equation for C.
