Apet store owner surveys 100 customers to find out what brand of dog food is purchased most frequently. a. population: 100 customers sample: dog food brand possible bias: not all customers buy that particular dog food brand c. population: pet store customers sample: 100 customers possible bias: not all customers have dogs b. population: 100 customers sample: pet store customers possible bias: not all customers shop at the pet store d. population: pet store customers sample: 100 customers possible bias: not all customers have pets