Which of the following relation represent Biot-Savart's law?

Options

A. `d vec(B)= (mu_(0))/(4pi) I(vec(d)l xx vec(r ))/(r )`
B. `d vec(B)= (mu_(0))/(4pi)I (vec(d)l xx vec(r ))/(r^(3))`
C. `d vec(B)= (mu_(0))/(4pi)I (vec(d)l xx hat(r ))/(r^(3))`
D. `d vec(B)= (mu_(0))/(4pi) I(vec(d) l xx vec(r ))/(r^(4))`