In a superconducting magnet, wires of superconducting material are embedded in the thick copper matrix, because while the material is in the superconducting state:

• A. The leakage current passes through the copper part
• B. Copper part helps in conducting heat away from the superconductor
• C. Copper part helps in overcoming the mechanical stress
• D. Copper acts as an insulating cover for superconductor.