To find $f(3)$ given the function $f(x+1) = 3x^2 - x + 4$, we first need to determine the value of $x$ that makes the argument of the function equal to 3. Step 1: Set the argument of the function equal to 3 and solve for $x$. $$ x+1 = 3 $$ $$ x = 3 - 1 $$ $$ x = 2 $$ Step 2: Substitute $x=2$ into the expression for $f(x+1)$. $$ f(3) = 3(2)^2 - (2) + 4 $$ Step 3: Perform the calculations. $$ f(3) = 3(4) - 2 + 4 $$ $$ f(3) = 12 - 2 + 4 $$ $$ f(3) = 10 + 4 $$ $$ f(3) = 14 $$ Comparing this result with the given options: A) 10 B) 16 C) 12 D) 14 The calculated value matches option D. The final answer is $\boxed{\text{D) 14}}$.