Explanation

(d) Let $x$ watt be the power loss in transmission line in the form of heat
$\therefore x = \left( \frac{P}{V} \right)^{2}R = \left( \frac{10 \times 1000}{200} \right)^{2} \times 0.2$
$= 500W = 0.5\ kW$
Efficiency of transmission
$= \frac{power\ delivered\ by\ line}{power\ supplied\ to\ line} = \frac{10\ kW}{10\ kW + x\ kW\ }$
$= \frac{10}{10 + 0.5} = \frac{10}{10.5} = 0.95 = 95\%$