Strings A and B have identical lengths and linear densities, but the tension T in string B is double of the tension TA in string A. The figure shows four situations, (a) through (d), in which standing wave patterns exist on the two strings. In which situations do strings A and B oscillate at the same resonant frequency? String A String B (a) ( b ) ( c ) ood ( d) O situation d none of them O situation b situation c O situation a