14) B

Distance of transmitter from abdomen = 10 cm = 0.1 m
Time taken to reach the abdomen = Distance ÷ Time = 0.1 ÷ 500 = 0.0002 s

Since the receiver is adjacent to the transmitter, distance from the abdomen to receiver must also equal 0.1m

Therefore, the time taken for the pulse to travel from the abdomen to the receiver must be equal to 0.0002 s.

Total time = 0.0002 + 0.0002 = 0.0004 s

0.0004 s = 0.4 ms