Answer
D. $P> Q>T>R=S$
Work Step by Step
Since all bulbs are same(resistance) so brightness will be proportional to potential difference across bulb.
potential difference across each bulb is
$V_P = \frac{5 }{8 }\varepsilon$
$V_Q= \frac{ 3}{ 8}\varepsilon$
$V_R = \frac{ 1}{ 8}\varepsilon$
$V_S = \frac{ 1}{ 8}\varepsilon$
$V_T = \frac{ 2}{8 }\varepsilon$
hence order of brightness i
$P> Q>T>R=S$
