1. The problem asks to find the value of the function $f(x)$ at $x = -2.3$ given the function $f(x) = 12$. 2. Since $f(x) = 12$ is a constant function, it means that for every input $x$, the output is always 12. 3. Therefore, $f(-2.3) = 12$ regardless of the value of $x$. 4. The correct answer is choice B: 12.