In which of the following pairs of metals are both commercially extracted from their respective ores by the carbon reduction method?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ In an Ellingham diagram,the oxidation of carbon to carbon monoxide shows a negative slope with respect to temperature.
Reason $R:$ $CO$ tends to get decomposed at higher temperature.
In the light of the above statements,choose the correct answer from the options given below:

The metallurgical process in which a metal is obtained in a fused state is called:

At a site,low grade copper ores are available and zinc and iron scraps are also available. Which of the two scraps would be more suitable for reducing the leached copper ore and why?

When silica is present as an impurity in an ore,a/an ........ flux is required.

Why is copper extracted from low-grade ores by hydrometallurgy?