Cellular mobiles work in the frequency range of:
(A) 840 to 935 MHz
(B) 3.7 to 4.2 GHz
(C) 420 to 890 MHz
(D) 30 to 300 GHz

Hint:All cell phone carriers use two common frequency bands. One type is ‘1900’ that uses the frequencies in the range 1850-1990. The other is ‘PCS’ which belongs to the 800 MHz band. That uses the set of frequencies in the 824-894 range. Most of the cellphones that we use work in either of these two bands.

Complete step by step answer:
Cellular frequencies are the frequency ranges included in UHF: ultra high frequency bands that are assigned for cellular phone use. It uses portions of the radio frequency spectrum allocated to the mobile service, to receive and transmit the signals. Hence we can say that it is included in the range 840 MHz to 935 MHz.
Hence, option A is the correct answer among the four.

Note:The IEEE defines the UHF radar band as frequencies belonging to a range between 300 MHz and 1 GHz. The major applications of this technology include personal radio services like Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications. Other applications of Ultra high frequencies include television broadcasting, land mobile radio systems, two-way radios, radars etc. The major advantage of this technology is that the transmitting antennas are small enough to be installed in portable devices. Hence, it can be incorporated into various devices that are being used in our daily lives.