The ((∂ E)/(∂ T))_P of different types of half cells are as follows: (Where E is the electromotive force) Which of the above half cells would be…

The $\displaystyle \left(\frac{\partial \mathrm{E}}{\partial \mathrm{T}}\right)_{\mathrm{P}}$ of different types of half cells are as follows :

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

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