To find the derivative of the function \( f(x) = 3x^2 + 4x + 5 \), we use the power rule of differentiation.
The derivative of \( 3x^2 \) is:
\[
\frac{d}{dx}(3x^2) = 6x
\]
The derivative of \( 4x \) is:
\[
\frac{d}{dx}(4x) = 4
\]
The derivative of the constant 5 is 0.
Thus, the derivative of \( 3x^2 + 4x + 5 \) is:
\[
f'(x) = 6x + 4
\]
Therefore, the correct answer is option (1).