Which of the following statements of magnetic field are correct in case of Biot-Savart's Law ?

Which of the following statements of magnetic field are correct in case of Biot-Savart's Law ?
A. Differential Magnetic field is inversely proportional to square of the distance between the point & element.
B. Differential Magnetic field is directly proportional to product of current element & cosine of angle between element and line connecting point.
C. Differential Magnetic Field is directly proportional to sum of square of distance between point and element.
D. Differential Magnetic Field is inversely proportional to product of current element & sine of angle between element and line connecting point.

a. Only A
b. Both A & D
c. Both C & D
d. B & D

Correct Answer : b. Both A & D

Explanation :

Biot- Savart's Law implies that differential magnetic field has an inverse relation to square of the distance between point & element along with the product of current element & sine angle between element & connecting point.