Answer:
Every frugal shopper counts his or her coupons before they shop.
Step-by-step explanation:
In the above sentence, the pronoun used would be 'his' or 'her' which would agree with the number of the antecedent. The antecedent is 'every frugal shopper' which is singular in number and hence, the pronoun used would be singular. The statement has a pronoun agreement error.