Question

which of the following could explain why the bulb did not light up?
a the bulb has fused.
b it is an open circuit.
c the batteries are connected in the wrong way.
d the batteries are drained.
(1) a and b only
(2) a and c only
(3) b and d only
(4) a, b and d only

Explanation:

The question asks for reasons a bulb does not light up. A fused bulb (A) breaks the circuit, an open circuit (B) has no continuous path for current, wrong battery connection (C) may reverse polarity but doesn’t always stop light, and drained batteries (D) have no voltage. Both A and B directly prevent current flow, so they are valid explanations.

Answer:

(1) A and B only