A new pet food product for small dogs has been developed to help with tooth decay. Fifty-two dogs participate in the study. Each dog owner picks a card from a standard deck out of a hat. If the card is red, their dog will be in the treatment group. If the card is black, their dog will be in the placebo group. Which experimental design was used?

a. Randomized Block Design
b. Completely Randomized Design
c. Case-Control Design
d. Matched-Pair Design