Group the objects into two categories.
Ball, shoe, pen, flower
Objects 1 and 2: Ball, Shoe 
Objects 3 and 4: Pen, Flower
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Group the objects into two categories.

### Response:
Objects 1 and 2: Ball, Shoe 
Objects 3 and 4: Pen, Flower