To determine the best classifiers for indicating a water bottle on a counter, it would depend on the specific context of the classifiers (CL:C, CL:B, CL:4, CL:5, CL:W) and what they represent. However, based on typical conventions in classification systems, a combination that includes a clear identifiable class for a water bottle would be ideal.
Given the options, CL:W and CL:C might be the best choice if CL:W specifically represents a water bottle and CL:C could represent the counter or a related context where the bottle is located.
Thus, the most suitable response would be:
CL:W and CL:C.