Which of the following sentences contains an incorrect pronoun shift?

A. Avery and Jerry brought their dad a slice of cake from dinner.
B. I thought I saw a dog bury their bone under the tree.
C. Betsy was so excited to get her car back from the mechanic.
D. Joe’s grandfather broke his favorite plate in the dishwasher.

B. I thought I saw a dog bury their bone under the tree.