A solid steel shaft of diameter d and length l is subjected to twisting moment I. Another shaft B of brass having same diameter d, but length l/2 is also subjected to the same moment. If shear modulus of steel is two times that of brass, the ratio of the angular twist of steel to that of brass shaft is
(a) 1 : 2 (b) 1 : 1 (c) 2 : 1 (d) 4 : 1