Chapter 4 - Inverse, Exponential, and Logarithmic Functions - 4.6 Applications and Models of Exponential Growth and Decay - 4.6 Exercises - Page 479: 1

$B$.

Step 1. the starting population is at $x=0$, thus $y_1=2e^{0.02(0)}=2$, Step 2. Let $y_2=2e^{0.02x}$ be the population after $x$ years, Step 3. to triple means $y_2=3y_1$, thus $2e^{0.02x}=3\times2$ Step 4. The answer is $B$.