How I interpret it?

stmt 1: You can only assume that volume after melting is reserved which is i am note sure of as i don't remember much from my school physics lectures.
Anyway, assuming this we get:

Volume of cube = volume of rectangular solid / 2 = (5x4x3)/2= 30
and also we can suggest that length of cube 1 = length of cube 2

therefore, L^3=30 => L approximately equals to 3.1 feet

With all this assuming we get that A is sufficient which is the OA.

But about B. Obviously it gives no useful information or am i wrong?

but my concern is that is my interpretation right?? since I did it after I checked the OA, I couldn't get it before as B is so misleading and it widen the scope of the question without need.

Please help.