Lời giải
\( \int_{0}^{3} f'(x) \, dx + \int_{0}^{3} f'(3 - x) \, dx = 5 \)
\( \Leftrightarrow f(x) \bigg|_{0}^{3} - f(3 - x) \bigg|_{0}^{3} = 5 \)
\( \Leftrightarrow f(3) - f(0) - \big[f(0) - f(3)\big] = 5 \)
\( \Leftrightarrow 2f(3) - 2f(0) = 5 \)
\( \Leftrightarrow 2f(3) = 6 \Leftrightarrow \quad f(3) = 3 \)
\(\Rightarrow\) Vậy chọn đáp án \(\boxed{\text{A}} \)