The colour of $\text{Cu}$ metal is:

Copper ($\text{Cu}$) is a transition metal known for its characteristic reddish-brown metallic luster.

• Why Option A is correct: Pure, unoxidized copper metal has a distinct reddish-brown color.
• Why Option B is incorrect: Blue is the characteristic color of hydrated copper ions ($\text{Cu}^{2+}\text{(aq)}$) in aqueous solutions (such as copper sulphate solution), not the metal itself.
• Why Option C is incorrect: Green is the color of basic copper carbonate formed when copper corrodes in moist air, or the color of iron(II) sulphate solution, not pure copper metal.
• Why Option D is incorrect: Grey is the typical color of many other metals like iron, zinc, and aluminium, but not copper.