Complete Question
The complete question is shown on the first uploaded image
Answer:
The correct option is option 3
Step-by-step explanation:
From the question we are told that
The diameter of solenoid 1 is
![d_1](https://img.qammunity.org/2021/formulas/mathematics/high-school/qswmp2ug99xmsijsl2zr6m267830l92giv.png)
The length of solenoid 1 is
![L_1](https://img.qammunity.org/2021/formulas/physics/college/vxcpx22e1ohqw81uu31yxh0xh50n7rc1m3.png)
The number of turns of solenoid is
![N_1](https://img.qammunity.org/2021/formulas/physics/college/eo9ct51a9h42zgsoolcsiyf9jwcu15b3k2.png)
The diameter of solenoid 2 is
![d_2 = 2d_1](https://img.qammunity.org/2021/formulas/physics/college/mu9kv0j38qu5hh3uvxtptz4dnubzpkownb.png)
The length of solenoid 2 is
![L_2 = 2L_1](https://img.qammunity.org/2021/formulas/physics/college/x95imjs9uq35gchc8101t3svvjnr10rgh1.png)
The number of turns of solenoid 2 is
![N_2 = 2 N_1](https://img.qammunity.org/2021/formulas/physics/college/phz80uu5lgo4u3kx3vk8d73x0jh6biwhbu.png)
Generally the magnetic in a solenoid is mathematically represented as
![B = (\mu_o * N * I )/(L)](https://img.qammunity.org/2021/formulas/physics/college/fwohp2ppe3rzui5k32pb6nn70qsq15o5tv.png)
From this equation we see that
![B \ \alpha \ (N)/(L)](https://img.qammunity.org/2021/formulas/physics/college/c8w1qc079qxbfh10dt9b9yoz26lbp3uagy.png)
![B = C (N)/(L)](https://img.qammunity.org/2021/formulas/physics/college/ri1ynbbptyo7749zuey71op15jcva3bucq.png)
Here C stands for constant
=>
![C = \frac{B * (L)/(N)]()
=>
![\frac{B_1 * (L_1)/(N_1) = \frac{B_2 * (L_2)/(N_2)]()
=>
![(B_1)/(B_2 ) = (N_1 L _2)/( N_2L_1)](https://img.qammunity.org/2021/formulas/physics/college/hgxl38546zrjhj4m3oy7wqsmbma46efrem.png)
=>
![(B_1)/(B_2 ) = (N_1 * (2 L_1))/( (2 N_2)L_1)](https://img.qammunity.org/2021/formulas/physics/college/9c2g2vuwpjrp320z1r8f0gblcn6z2sjgdo.png)
=>
![(B_1)/(B_2 ) = 1](https://img.qammunity.org/2021/formulas/physics/college/6kz3vha5e1u88n3i5kozg94u5vcqn154tu.png)
=>
![B_2 = B_1](https://img.qammunity.org/2021/formulas/physics/college/egwdgigt9jtrkaohi604wyf9xyez5046cn.png)