When a fuse is rated 8A, it means:
A) it will not work if current is less than 8A
B) it has a resistance of 8 $\Omega$
C) it will work only if current is 8A
D. it will burn if current exceeds 8A

Hint: A fuse is an electrical component. This acts as a protector by maintaining the current flow in the circuit. This is helpful in avoiding the short circuits, overloading, or mismatched loads which might cause severe damage to the electrical appliances.

Complete step-by-step solution:
The fuse is a metal strip, which has resistance to heat and temperature which is caused due to the flow of current in the circuit. This is generally mounted in between a pair of electrical terminals. This is usually connected in series, as we know that in series if the current flow is stopped, then no other appliance or load connected in the circuit, receives the current. This has high resistance and generates heat when current is passed through them. When the heat of the fuse exceeds its threshold, it gets melted as a precautionary step. The fuse strip is made of an alloy of zinc, copper, and aluminum, to get the desired properties. The fuse is generally surrounded by air or silica sand, which acts as a non-conducting liquid and helps in the breaking of the fuse.
A fuse acts as a barrier when some overcurrent accidentally passes through the circuit. This is done by the melting of the fuse, which breaks the connection of the circuit.
Thus when we say that the fuse is rated \[\text{8A}\], we mean that if the current exceeds \[\text{8A}\], then the fuse breaks to prevent any accidents.
Hence the answer is option D. it will burn if current exceeds \[\text{8A}\]

Note: Excess currents in a circuit are highly dangerous, as they can cause short circuits, which in turn can cause electrical fires. Thus for the safety of the residents, the fuse is set up in every building, like houses, malls, and hotels. However, big buildings like hotels, malls, and hospitals have many fuses.