Explanation:

- Silver: Known for its excellent conductivity, silver has a low resistivity.

- Nichrome: A common alloy in heating elements, Nichrome has high resistivity. This property makes it suitable for producing heat.

- Chromium: Although it's a metal, chromium's resistivity is higher than that of copper or silver but still lower than Nichrome’s.

- Iron: Has moderate resistivity, higher than that of silver but lower than Nichrome.

Nichrome has the highest resistivity among the listed options.