Answer:
A.
Step-by-step explanation:
The equation of Magnetic Field is given by
![B= (\mu_0 NI)/(L)](https://img.qammunity.org/2020/formulas/physics/college/bmc1gtkqgx6u4fed1crigrxzhsklfi5p3i.png)
Where
![L= Lenght](https://img.qammunity.org/2020/formulas/physics/college/cnciq65qh8bbt5ttcnjew7tqixwamz4qh3.png)
Number of loops
I= current
constant of permeability of free space
As you can note, the magnetic field does not depend upon radius of the solenoid, therefore it would remain in same