The correct answer is C. Cdma2000 1xEV-DO is not backward compatible with Cdma2000.
Cdma2000 is a third-generation (3G) cellular technology that was developed by Qualcomm. It is a direct descendant of the second-generation (2G) CDMAOne technology, and it is designed to provide higher data rates and capacity than 2G. Cdma2000 is used in a variety of countries around the world, including the United States, Canada, Japan, and South Korea.
Cdma2000 is a family of technologies, and there are several different variants of Cdma2000. The most common variants are Cdma2000 1xRTT, Cdma2000 3xRTT, and Cdma2000 1xEV-DO.
Cdma2000 1xRTT is the first-generation Cdma2000 technology. It is a 1.25-megabit-per-second (Mbps) technology that is backward compatible with CDMAOne.
Cdma2000 3xRTT is the second-generation Cdma2000 technology. It is a 3.1 Mbps technology that is not backward compatible with Cdma2000 1xRTT.
Cdma2000 1xEV-DO is the third-generation Cdma2000 technology. It is a 14.4 Mbps technology that is not backward compatible with Cdma2000 1xRTT or Cdma2000 3xRTT.
Cdma2000 1xEV-DO is not backward compatible with Cdma2000 because it uses a different modulation scheme. Cdma2000 1xRTT and Cdma2000 3xRTT use a modulation scheme called QPSK, while Cdma2000 1xEV-DO uses a modulation scheme called OFDM. OFDM is a more efficient modulation scheme than QPSK, and it allows Cdma2000 1xEV-DO to achieve higher data rates.
However, the use of OFDM also means that Cdma2000 1xEV-DO is not backward compatible with Cdma2000 1xRTT and Cdma2000 3xRTT. This is because Cdma2000 1xRTT and Cdma2000 3xRTT base stations are not able to decode OFDM signals.
As a result, Cdma2000 1xEV-DO users cannot connect to Cdma2000 1xRTT or Cdma2000 3xRTT networks, and Cdma2000 1xRTT and Cdma2000 3xRTT users cannot connect to Cdma2000 1xEV-DO networks.