Which of the following shapes can be folded into an open cube box ?

 

In an open cube box, one of the face of a cube is missing.

So, we need exactly 5 square faces to make an open cube box instead of 6 faces as in a closed cube box.

Now, counting the number of faces of each given shapes, we get :-

         shape A : 6 square faces

         shape B : 5 square faces

         shape C : 6 square face

         shape D : 6 square faces

         Hence, the correct option will be option B.