Consider the following statements :
1. Superconductors exhibit normal conductivity behaviour above a transition temperature Tc.
2. Superconductors lose their superconducting nature in an external magnetic field, provided the external magnetic field is above a critical value.
3. High Tc superconductors have Tc values in the range 1 to 10 K.
Which of the above statements are correct ? (a) 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3