OKValve Company Applies for a Patent for a Valve

O.K.Valve Company applies for a patent for a valve.Meanwhile,O.K.licenses its products,including the valve,to Petro Pumps,Inc. ,which uses the valve to make oil pumps.Under the terms of the license,Petro agrees to pay royalties on O.K.'s "patented" products.When a patent is granted on the valve,O.K.asks Petro to pay royalties on the sales of its pumps.Petro wants to challenge the validity of O.K.'s patent.According to the majority in MedImmune,Inc. ,v.Genentech,Inc.case,a patent licensee can challenge the validity of a licensed patent

A) only after breaching the license agreement.
B) only before breaching the license agreement.
C) without breaching the license agreement.
D) under no circumstances.