The correct option is B 0.06775m3
Given,
The internal length, breadth and height of a closed box are 1m=100cm,80cm and 25cm respectively.
As its sides are made of 2.5cm , the external length, breadth and height of the closed box are 100+2(2.5)=105cm,80+2(2.5)=85cm and 25+2(2.5)=30cm respectively.
Now, volume of wood used to make the box = Volume with the external dimensions − Volume with the internal dimensions
=> Volume of wood used to make the box =(105×85×30)−(100×80×25)=267750−200000=67750cucm=0.06775m3