Betty Plaintiff's Law Firm Has Hired an Associate from an Out-Of-Town

Betty Plaintiff's law firm has hired an associate from an out-of-town office of Defendant #1's law firm. When Defendant #2's law firm discovers this conflict of interest, they (Defendant #2's law firm) brings a Motion to disqualify Plaintiff's law firm. The ruling of the court will probably be

A) There is no problem unless the newly hired associate is working on the case.
B) Defendant #1 is the harmed party. Unless that party brings the motion,the court will not rule against Plaintiff because only Defendant #1 is potentially harmed by the conflict.
C) There is no problem because the associate is from an out-of-town office.
D) Everyone involved in the case is harmed so Plaintiff's counsel will be disqualified.