Code Division Multiple Access (CDMA) technology is primarily used in:

CDMA (Code Division Multiple Access) is a channel access method used in wireless mobile telecommunications. It allows multiple users to share the same frequency band simultaneously by assigning each user a unique digital code, enabling efficient mobile phone communication. CDMA was widely adopted in 2G and 3G mobile networks (e.g., Qualcomm's IS-95, CDMA2000). It has no application in X-ray imaging, AI algorithms, or photocopying. Hence option (a) is correct.