AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
(A) Both A and R are true and R is the correct explanation of A.
Tungsten is used for bulb filaments because of its very high melting point (3380°C), which prevents it from melting even at incandescent temperatures.
Source: Chapter 11, Section 11.7.1
The passage explicitly states that "a strong metal with high melting point such as tungsten (melting point 3380°C) is used for making bulb filaments." Note: the Reason mentions high resistivity as well — tungsten does have relatively high resistivity among metals, which helps generate sufficient heat/light. Both properties are relevant and R correctly explains A, so option (A) is correct. Watch out for option (B) — examiners test whether students recognise that R genuinely explains A, not just that both are true.