Final answer:
Remote receiving systems are connected to emergency services telecommunications centers mostly through a telephone line or dedicated radio frequency, enabling consistent and efficient communication.
Step-by-step explanation:
The question relates to the connectivity options for remote receiving systems to an emergency services telecommunications center. The correct answer is D. A telephone line or dedicated radio frequency. Devices such as cell phones utilize radio receivers and transmitters that can tune into assigned microwave frequencies. The signal's low intensity restricts its range, promoting the efficiency of communication within specific areas called cells. This ground-based cellular system connects the device to a local broadcast tower and enables smooth transitions between towers as the phone user moves from one area to another, ensuring continuous communication. Therefore, remote receiving systems are typically connected to emergency telecommunications centers via telephone lines or dedicated radio frequencies, which provide the necessary reach and reliability for emergency communication.