Aluminum strips of 2mm thickness are joined together by resistance spot welding process by applying an electric current melting aluminum is 2.9J/mm3. the diameter and thickness of the weld nugget are found to the electrical resistance to be 75 micro-ohms, the percentage of total energy utilized in forming the weld nugget is
(a) 28 (b) 35
(c) 65 (d) 72