For complex procurement items , often contract negotiation can be an independent process . An example of an input if such a process is used is:?

first of all you have to have an approved CAPEX with a budget  so ... I would say a, b, c and d for sure

Meaning you need an proved CAPEX with a caped budget which includes the open items list ... the open item list usually comes from the vendor (manufacturer) from whom the expert judgment/recommendation comes... usually identified by the urgency of an item and how long it lasts during a production cycle...

To summarize this you need all4 processes... I think this statement is true not only refurbishing machinery 

Procurement cycle begins with :  the need for item/services/Capex etc......Once this is done and requirement is raised then comes the role of Procurement department to Raise a Requisition and float the inquiries - Receive the quotations- Evaluate the quotations , discuss with the users - then do the negotiations (Price, Quality, Delivery, terms of payment etc) ....Raise Purchase Orders and get approvals .

It means all of the above is required.

Option    A   :

An example of an    input     if such a process is used is      Open items list , 

An example of an     output      if such a process is used is   Documented decisions

All of the choices A, B, C, and D are a correct answers for my opinion.

Answer D is most likely in complex situation ,

All of the items but more so to do with B, C and D

Do you want some help with your PMP certification? The first thing is: there's only one correct answer, albeit they might seem very identical. So the choice resides in precedence  of the options given: if you think what should happen in time you'll find the correct answer. This is a very good aproch for future certifications exams. In this case inputs occur at the beginning of each process so the answer is quite easy ;-)