Question

Please give me answer of this question as soon as possible I really need it

Answer 1

Answer-

Option D✔️✔️✔️

Answer 2

Formula for Magnetic Field at centre by complete Circular Coil is

B = μ I / 2 a

But in question, it is 3/4th of the complete circular loop.
So magnetic induction will also be the 3/4th

Thus answer is
$B' = \frac{3}{4} B$

$B' = \frac{3}{4} ( \frac{μ I}{2a} )$

$B' = \frac{3μI}{8a}$

Option D.