Which reference electrode is used to measure the electrode potential of other electrodes?

For a cell constructed with $Cu$ and $Ag$ electrodes,which of the following statements is correct regarding the cathode and the standard cell potential $(E_{cell}^{\circ})$?

Given are $E^{\circ}$ values for some half reactions:
$I_2 + 2e^{-} \to 2I^{-}$ ; $E^{\circ} = 0.54 \, V$
$MnO_4^{-} + 8H^{+} + 5e^{-} \to Mn^{2+} + 4H_2O$ ; $E^{\circ} = 1.52 \, V$
$Fe^{3+} + e^{-} \to Fe^{2+}$ ; $E^{\circ} = 0.77 \, V$
$Sn^{4+} + 2e^{-} \to Sn^{2+}$ ; $E^{\circ} = 0.1 \, V$
The strongest reducant and oxidant respectively are:

The standard electrode potential is measured by

Review the $SRP$ (at $25\,\text{°C}$) data in acidic medium:
$Ti^{4+} + e^- \to Ti^{3+}, \, E^o = -x \text{ V}$
$Fe^{3+} + e^- \to Fe^{2+}, \, E^o = -y \text{ V}$
where $x < y$,point out the wrong statement.

The $(\frac{\partial E}{\partial T})_P$ of different types of half cells are as follows:

$A$	$B$	$C$	$D$
$1 \times 10^{-4}$	$2 \times 10^{-4}$	$0.1 \times 10^{-4}$	$0.2 \times 10^{-4}$

(Where $E$ is the electromotive force)
Which of the above half cells would be preferred to be used as reference electrode?