The radius of the circular conducting loop shown in figure is $R$. Magnetic field is decreasing at a constant rate $\alpha$. Resistance per unit length of the loop is $\rho$. Then current in wire $A B$ is ( $A B$ is one of the diameters)

• A

  $\frac{R \alpha}{2 \rho}$ from $B$ to $A$
• B

  $\frac{R \alpha}{2 \rho}$ from $A$ to $B$
• C

  $\frac{2 R \alpha}{\rho}$ from $A$ to $B$
• Correct answer
  D

  zero

Hence, the correct answer is option: 'D'.