I'm getting my ball in just over a week and am just purchasing the last of his stuff so I'm all set up before he gets here. He'll be 4 weeks old wen I get him, which of these sizes for a water bowl is more appropriate?

12 x 10 cm: 16.6 x 16.4 x 10.2 cm

11 cm: 12.4 x 12 x 12 cm

8 cm: 12.6 x 12.2 x 12 cm

Thanks.