‌ (d) Let length, breadth and height of a room are ‌3x, 2x‌ and ‌x,‌ respectively. ‌ ‌ Then, ‌‌ volume of room ‌=1296 ⇒‌‌‌‌3x×2x×x=1296 ⇒‌‌6x3=1296 ⇒‌‌x3=216 ∴‌‌x=6 ∴‌ Breadth of room ‌=2x=2×6=12m