题目：
(56) is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.
(57) is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.
(58) is an approach preferred by cable TV providers. In this solution the fiber terminates at an opto-electrical converter and the final segment is a shared coaxial cable.
(59) is a device used to connect two separate network that use different communication protocol.
(60) is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.
A．ADSL
B．FTTC
C．HFC
D．FTTH
答案：
参考答案：C
解析： 是有线电视提供商的首选途径，在这种解决办法中光纤止于光电转炉，最后一段使用同轴电缆。
