The correct option is Silver.
Explanation
Electrical resistivity ($\rho$) is an intrinsic property of a material that measures its opposition to the flow of electric current. There is an inverse relationship between resistivity and conductivity: materials with low resistivity are good conductors, while materials with high resistivity are insulators.
Analysis of Options:
- Silver: Silver is the best conductor of electricity among all metals at room temperature. It possesses the lowest electrical resistivity (approximately $1.60 \times 10^{-8} \, \Omega \cdot \text{m}$).
- Iron: Iron is a conductor, but it offers more resistance to current flow compared to silver or copper. Its resistivity is higher (approximately $1.0 \times 10^{-7} \, \Omega \cdot \text{m}$).
- Nichrome: This is an alloy of nickel, chromium, and iron. Alloys generally exhibit higher resistivity than pure metals. Nichrome has a high resistivity (approximately $1.1 \times 10^{-6} \, \Omega \cdot \text{m}$), which makes it suitable for heating elements.
- Glass: Glass is an insulator. It has an extremely high electrical resistivity (ranging from $10^{10}$ to $10^{14} \, \Omega \cdot \text{m}$), effectively preventing the flow of current.
Key Takeaway:
Among common materials, Silver has the lowest electrical resistivity and highest conductivity. The order of resistivity from lowest to highest for the given options is: Silver < Iron < Nichrome < Glass.