When Skyler Was First Training His Dog,Smooches,to Heel,he Would Give

Multiple Choice

When Skyler was first training his dog,Smooches,to heel,he would give Smooches a treat when she stayed close during walks.Now Smooches stays right by Skyler's side,even when she is not on her leash.Which statement best describes this situation

A)  Staying close was a negative reinforcer for receiving dog treats. 
B)  The dog treats were negative reinforcers for staying close. 
C)  Staying close was a positive reinforcer for receiving dog treats. 
D)  The dog treats were positive reinforcers for staying close.