Final answer:
The sentence with incorrect pronoun-antecedent agreement is A) No one in the crowd had noticed the pickpocket stealing their wallet, as 'their' is plural and 'no one' is singular.
Step-by-step explanation:
The sentence with an incorrect shift in pronoun-antecedent agreement is A) No one in the crowd had noticed the pickpocket stealing their wallet. The pronoun 'their' is plural, while its antecedent 'no one' is singular. The pronoun should agree in number with its antecedent, which means that 'their' should be 'his or her' to make it singular.