Assertion (A) Redox couple is the combination of oxidised and...

Both assertion and reason are true reason is the correct explanation of assertion. Redox couple is the combination of oxidised and reduced form of substance. In the representation (E_{$\mathrm{Fe}^{3+}$/ $\mathrm{Fe}^{2+}$}^0) and (E_{\mathrm{O}^{2+}}^0 / $\mathrm{Ou}^{1-} \mathrm{Fe}^{3+}$/ $\mathrm{Fe}^{2+}$) and ($\mathrm{Cu}^{2+}$/ $\mathrm{Cu}$) are redox couples.