A company has developed a new sensing device that, according to the company' s claims, detects weak, ultralow-frequency electromagnetic signals associated with a beating heart. These signals, which pass through almost any physical obstruction, are purportedly detected by the device even at significant distances. Ttherefore, if the company's claims are true, their device will radically improve emergency teams ability to locate quickly people who are trapped within the wreckage of collapsed buildings. Which of the following, if true, most strengthens the argument?
A: Ultralow-frequency signals are not the only electromagnetic signals that can pass through almost any physical obstruction.
B: Most People who have survived after being trapped in collapsed buildings were rescued within two hours of the building's collapse.
C: Extensive training is required in order to operate the device effectively.
D: The device gives a distinctive reading when the signals it detects come from human beings rather than from any other living beings.
Choose A, B, C or D as your solution.
D