Here's why:
* Pronoun: "She" is a pronoun, which replaces a noun to avoid repetition.
* Antecedent: The antecedent is the noun that the pronoun refers to.
* Connection: The sentence tells us that Mrs. Wilton went to the market and then had to pick up her daughter. The pronoun "she" clearly refers to Mrs. Wilton, who is the subject of the first part of the sentence.
