Which One of the Following Sentences Has a Missing or Unclear

Which one of the following sentences has a missing or unclear antecedent?

A) Kathy wanted to tell Alyssa and Sally, but she couldn't keep a secret.
B) Older people are always telling me to think about the consequences.
C) I saw both stunts on television, but the second stunt was too hard to perform.
D) Miranda left her report and lunch on the counter, but her lunch is now missing.