During an ultrasound, sound waves are sent by a transducer through muscle tissue at a speed of 1,300 m/s. Some of the sound waves are reflected from a metal fragment 3.0 cm into the muscle tissue. How long did it take the transducer to detect the reflected waves from the metal fragment after they were first emitted? a 23 seconds b 39 seconds c 4.6 E5 seconds d 7.8 E5 seconds