If Congleton had been forced to assign those people to the project, that shows we cannot infer anything about Congleton’s state of mind or purpose from that assignment. So, (A) must be assumed.

Whether the project actually can or will fail is irrelevant. The argument concerns only whether Congleton wanted the project to fail and whether her hiring decisions indicate that desire.

If Congleton knew that the people assigned wouldn’t work well together, that could show how she could have thought her assignments would not produce good results, despite the individual excellence of each employee.

If this possibility were true, then the witness was not necessarily lying when he said what he said about Congleton. So, this possibility would undermine the argument.

If this possibility were true, this shows how she could have thought her assignments would not produce good results, despite the individual excellence of each employee.