The correct answer is 'Change Request'.  I think it's terminology that's causing some problems...  BABOK (for better or worse) uses 'solution' in the broad sense, so 'solution' does not = 'system'.  I believe the intent is that the end goal is a business solution that meets business needs, of which technology is some of that overall solution.  So it might help in the context of this question to think of the input as 'business solution scope'.... 

And I think that there is an underlying premise that you start at a high-level, so business solution scope at the start of elicitation could be relatively broad.

Sandy

I agree with Kimbo and cisco.leon. You cannot really determine the solution scope without eliciting some requirements. The confusion arises from the very broad meaning assigned to solution scope in this question. There is no way for me to determine what's in scope and what's out of scope until I have my head around the business requirements. Once I do have some feature requests or business goals or business requirements identified, I can then work with the team and stakeholders to determine what sounds like a plausible scope for a particular iteration or phase or release or sprint. Once I have the scope of business requirements, I can then work with the development team to drive out technical and functional requirements. So yes, scope can serve as an input to technical requirements elicitation in this particular example.

I may also need to elicit requirements if a stakeholder has submitted a change request. For instance, the initial requirement may have been "take me to the moon". The stakeholder may change it to "I would like to go to Mars instead". Now I have to elicit and analyze requirements to fulfill this change request. So see, here "Change Request" was an input to "Requirements Elicitation".

I have realized that I need to dumb myself down and really not try to analyze things too much to make myself reach the same conclusions as the authors of BABOK. Logic hasn't served me well when it comes to CBAP questions.

One example is a question that asks you to calculate the number of connections needed in a network with "n" nodes. There really is no way of determining this unless I know the network topology e.g. point to point, star, ring, and whether I am trying to calculate the minimum number of connections needed. Really just high school level CS stuff. I don't think authors of these questions are familiar with any of that.