Which one of the following is the CORRECT expression for Biot-Savart law?

• A. \(\oint B \cdot dl = {\mu _0}\sum I\)
• B. \({\phi _E} = \frac{q}{{{\varepsilon _0}}}\)
• C. \(dB \propto \frac{{idl\sin \theta }}{{{r^2}}}\)
• D. \(dB = \frac{{i{r^2}\sin \theta }}{{dl}}\)