Explanation

(d)
In $\frac{N}{1000}\$KOH solution$,\ \left\lbrack OH^{-} \right\rbrack = 10^{- 3}\ M$
$pOH = - \log{\left\lbrack OH^{-} \right\rbrack = - \log\left\lbrack 10^{- 3} \right\rbrack}$
$= + 3\log{10 = 3}$
$pH + pOH = 14$
$pH = 14 - pOH$
$= 14 - 3$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 11$