Answer: b. Combine physical contact with verbal praise
Step-by-step explanation:
This is the best option of the options listed. Combining physical contact with verbal praise can have the effect of augmenting the verbal praise and giving it more power so to speak. For example, saying congratulations and then shaking a person's hand can really increase the weight of the congratulatory remark.
Using this method instead of the other options will help avoid confusion in the child as well as reduce the chance of the praise becoming meaningless as it was said one too many times.