The correct answer is: Year.
IMT-2000 is the third generation of mobile telecommunications technology. It was developed in the late 1990s and early 2000s, and it was first deployed in 2001. IMT-2000 is a family of standards that includes UMTS, CDMA2000, and TD-SCDMA.
The number 2000 in IMT-2000 signifies the year in which the technology was first deployed. This is in contrast to previous generations of mobile telecommunications technology, which were named after the decades in which they were developed. For example, the first generation of mobile telecommunications technology was called 1G, and the second generation was called 2G.
The other options are incorrect because they do not accurately reflect the meaning of the number 2000 in IMT-2000. Option A, “Number of subscribers per cell,” is incorrect because IMT-2000 does not specify a specific number of subscribers per cell. Option B, “Number of cells,” is incorrect because IMT-2000 does not specify a specific number of cells. Option C, “Area (Km),” is incorrect because IMT-2000 does not specify a specific area.