The correct answer is A. 2 – e-0.2t.
The differential equation is separable, so we can write it as $dx = (10 – 0.2x) dt$. Integrating both sides gives $x = 10t – 0.1x^2 + C$, where $C$ is an arbitrary constant. Using the initial condition $x(0) = 1$, we can solve for $C$ to get $C = 2$. Therefore, the solution is $x(t) = 10t – 0.1x^2 + 2$.
Option B is incorrect because it does not include the term $10t$. Option C is incorrect because it does not include the term $-0.1x^2$. Option D is incorrect because it has the wrong sign in front of the exponential term.