Assertion (A): The filament of an electric bulb is made of tungsten.
Reason (R): Tungsten has a very low melting point.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Assertion (A) is correct, but Reason (R) is not correct.
In an Assertion-Reason question, each statement is checked for truth first, and then R is tested as the cause of what A describes.
Assertion — correct. The filament of an ordinary electric bulb is a thin coil of tungsten.
Reason — not correct. Tungsten has a very high melting point (about 3400 °C), which is why it can glow white-hot without melting.
Since R is false, it cannot explain A.