Answer: B) the plaintiff.
Step-by-step explanation:
Plaintiff is t person in terms of agreement who files a lawsuit in the court.He/she can also be considered as complainant or suer .Plaintiff is provided with legal remedy,advice and results for their complaint.
According to the question,Jane is plaintiff as she is filing case against Jill for not fulfilling Jane's contract condition.Thus , she wants to attain refund for roses through legal procedure of court.
Other options are incorrect because Jane is not persuasive authority,defendant and binding party in the case.Thus, the correct option is option(B).