Decision Modeling and Analysis

Ajax is about to embark on a project involving the design, manufacture and introduction of a new microwave oven.  The first three activities and the immediate predecessors are:
 
  Activity Predecessor
  A  Prototype Design none
  B Acquisition of Materials A
  C Prototype Construction B

However, it has not yet been decided whether the prototype materials will be purchased from a vendor (taking two weeks) or produced in another Ajax division (four weeks).  What are the implications of this regarding usage of any standard project scheduling technique?