What is the difference between Bluetooth and WI-Fi devices ?

• A. Bluetooth used 2.4 GHz radio frequency band whereas Wi-Fi can use 2.4 CHz or 5 GHz frequency band
• B. Bluetooth is used for wireless local area networks (WLAN) only whereas Wi-Fi is used for wireless wide area networks (WWAN) only
• C. When information is transmitted between two devices using bluetooth technology, the devices have to be in the line of sight of each other, but when Wi-Fi technology is used the devices need not be in the line of sight of each other
• D. The statements (a) and (b) given above are correct in this context