The correct answer is: B. Limited coverage area
Cordless telephones use radio waves to transmit signals between the base unit and the handset. This means that they are limited by the range of the radio waves. If you move too far away from the base unit, you will lose your connection.
Wireless technology is not a drawback for cordless telephones. In fact, it is one of the main advantages of cordless telephones. Wireless technology allows you to move around your home or office without being tethered to a phone cord.
Mobile is not a drawback for cordless telephones. Cordless telephones are mobile in the sense that you can move around your home or office with the handset. However, they are not mobile in the sense that you can take them with you outside of your home or office.
Security is not a drawback for cordless telephones. Cordless telephones use the same security features as regular landline telephones. This means that they are protected from eavesdropping and other security threats.
In conclusion, the correct answer is: B. Limited coverage area.