If $f: \mathbb{R} \to \mathbb{R}$ is defined by $f(x) = 3x + 2$, then $f(f(x))$ equals:

Step-by-step Solution:

Given $f(x) = 3x + 2$

We need to find $f(f(x))$:

$$f(f(x)) = f(3x + 2)$$

$$= 3(3x + 2) + 2$$

$$= 9x + 6 + 2$$

$$= 9x + 8$$

Hence, Option A is correct.