The allocation of requirements is not an input to the solution scope definition, but a task that will use the solution scope as an input. The allocation of requirements is the process of assigning the requirements to solution components, such as features, functions, modules, etc. The allocation of requirements helps to ensure that the solution components are aligned with the requirements and that the requirements are traceable throughout the project lifecycle. The other options are correct inputs to the solution scope definition, as they provide the information and guidance needed to define the boundaries and characteristics of the solution that will address the business problem or opportunity. The required capability describes what the solution must be able to do to meet the stakeholder needs. The assumptions and constraints identify the factors that affect the feasibility, desirability, or viability of the solution. The business need defines the problem or opportunity that the solution aims to resolve or exploit. References:
Solution Scope - An Insight
BABOK Chapter 7: Requirements Analysis and Design Definition
The quick guide to defining project scope-in 8 steps