A copper wire (Y = 1 × 1011 N/m2) of length 6 m and a steel wire (Y = 2 × 1011 N/m2) of length 4 m each of cross-section 10-5 m2 are fastened end to end and stretched by a tension of 100 N. The elongation produced in the copper wire is
(A) 0.2 mm
(B) 0.4 mm
(C) 0.6 mm
(D) 0.8 mm