Magnetism

Electrical resistance of certain materials, known as superconductors, changes abruptly from a non-zero value to zero as their temperature is lowered below a critical temperature T_c(0). An interesting property of superconductors is that their critical temperature becomes smaller than T_c(0), if they are placed in a magnetic field, that is, the critical temperature T_c(B) is a function of the magnetic field strength B. The dependence of T_c(B) on B is shown in the figure.

In the graph below, the resistance R of a superconductor is shown as a friction of its temperature T for two different magnetic fields B₁ (solid line) and B₂ (dashed line). If B₂ is larger than B₁ which of the following graphs shows the correct variation of R with T in these fields?