QusGSM (Global System for Mobile communications) is developed in? Qusजीएसएम (मोबाइल संचार के लिए वैश्विक प्रणाली) विकसित किया गया है?

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A. 1970s
B. 1960s
C. 1980s
D. 1990s

Solution

D. 1990s

Explanation

Mobile services based on GSM were first launched in Finland in 1991. That same year, the GSM standard frequency band was expanded from 900 MHz to 1,800 MHz.