For forming the circular shadow the object should have a circular shape.

● Option (a) : A ball is circular in shape hence it can form a circular shadow.

● Option (b) : A flat disc is circular in shape hence it can also form a circular shadow.

● Option (c) : A shoe box is not circular in shape hence it cannot form a circular shadow. Therefore it is the correct answer.

● Option (d) : an ice cream cone is circular in shape hence it can also form a circular shadow.