Which sentence contains an antecedent that is unclear, missing, or confusing?
a. Aunt Ellie and I love quilting, but she prefers to use a machine instead of a needle.
b. I tried to interest the newspaper in the issue, but they weren't interested.
c. On the sheet handed out at the first meeting, our responsibilities were clearly outlined.
d. When you and your friends hear this African music, you'll love it.