Explanation

(c) Total resistance of the circuit $= \frac{80}{2} + 20 = 60\ \Omega$
$\Rightarrow$ Main current $i = \frac{2}{60} = \frac{1}{30}A$
Combination of voltmeter and $80\Omega\ $resistance is connected in series with $20\Omega$, so current through $20\Omega$ and this combination will be same $= \frac{1}{30}\ A$
Since the resistance of voltmeter is also $80\Omega$, so this current is equally distributed in $80\Omega$ resistance and voltmeter [$i.e.\frac{1}{60}A$ through each]
P.D. across $80\Omega$ resistance $= \frac{1}{60} \times 80 = 1.33V$