Fuse is a piece of wire of a material with a very low melting point. When a high current flows through the circuit due to overloading or short circuit, the wires gets heated and melts. As a result, the circuit is broken and current stops flowing.
The fuse must always be connected to the mains and it must be of correct value. For example, a 15-ampere fuse should trip when the current through it exceeds 15 amperes. A 20-ampere fuse should blow when the current through it exceeds 20 amps.
In this case, the electrical appliance is of 1100 W power and 220 V. So the current that passes through the appliance is calculated from P=VI. That is, I=P/V.
So, I = 1100 W/220 V = 5 A.
Hence, the wire B with current rating of 6 A should be used for the fuse.