Concept:A cube has all edges equal. Its volume = length × breadth × height = side × side × side.Formula used:V=s3, where s is the length of one side.Given:s=5 mSolution:V=5×5×55×5=25, then 25×5=125V=125 m3 (volume is in cubic metres because three lengths in metres are multiplied).Key point:25 m2 is the area of one face (s2), not the volume.Answer:Option D (125 m3)