Which of the following shapes can be folded into a cube ?

 

A cube is a solid three-dimensional shape having 6 square faces, 8 vertices and 12 edges. All the faces of a cube is in square shape. So we need exactly 6 squares faces to form a closed cube. 

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

shape A : 6 square face

shape B : 5 square face

shape C : 5 square face, 1 triangle face and 1 semi-circle face

shape D : 5 square face and 1 triangle face

Hence, the correct option will be option A because it has exactly 6 number of square faces.