Of the 25 households in a neighborhood, 17 have at least one dog. There are 19 dogs in the neighborhood . The owners walk their dogs at least 3 times a day . The number of times an owner walk his dog changes from Day to day Which of the quantities listed below are not variable quantities?
A. the number of dogs in the neighborhood
B. the number of households in the neighborhood
O C. the number of times an owner walks his dog in one day