Fuses and circuit breakers are connected in with the load and all other components in the circuit.

series

Explanation:

the fuse and circuit breakers  are protective devices meant to protect all loads and components in a circuit, therefore current has to pass trough them before getting to the loads and components and hence they are connected in series. If current that comes trough the fuse is above its required rating, the fuse will cut and if its the breaker it will trip off, hence preventing flow of current and damage to other loads and circuitry.    

b.

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