Match the difference of greatest and least value of the functions $f$ on L.H.S
(a) $\sin x \sin 2 x$ on $(-\infty, \infty)$
(b) $2 x^{3}-3 x^{2}-12 x+1$
on $[-2,5 / 2]$
(c) $\cos ^{-1} x^{2}$ on $[-\sqrt{2} / 2, \sqrt{2} / 2]$
(d) $x+\sqrt{x}$ on $[0,4]$
(p) $\pi 6$
(q) $8 / 3 \sqrt{3}$
(r) 6
(s) 27