If $\int_{0}^{1} \frac{1}{\sqrt{3+x}+\sqrt{1+x}} \, dx = a + b\sqrt{2} + c\sqrt{3},$ where $a, b, c$ are rational numbers, then $2a + 3b - 4c$ is equal to:
\( 4\)
\( 8 \)
\( 7 \)
\( 10 \)