The BA should confirm elicitation results by researching the actual concurrent users on the existing system and review findings with stakeholders after finding that the number of concurrent users is a large portion of the target user group, which seems high. This means that the BA should verify and validate the non-functional information for the system's replacement by comparing it with the factual data from the current system and discussing it with the stakeholders who provided it. Confirming elicitation results can help to ensure the accuracy, completeness, clarity, and consistency of the information.
The other options are incorrect because:
Option A is incorrect because observing a user performing the task to determine the length of time to complete the task is not an action that the BA takes after finding that the number of concurrent users is a large portion of the target user group, which seems high, but an action that the BA takes to elicit information from stakeholders by watching them perform their tasks or roles. Observing a user performing the task can help to understand how they interact with the system or solution.
Option B is incorrect because documenting the elicitation results in the solution requirements specification then seeking verification and validation in a requirements review is not an action that the BA takes after finding that the number of concurrent users is a large portion of the target user group, which seems high, but an action that the BA takes to record and communicate the elicitation results to stakeholders and ensure that they meet their needs and expectations. Documenting the elicitation results in the solution requirements specification can help to define and document the features, functions, and characteristics of the system or solution.
Option C is incorrect because conducting additional stakeholder analysis to determine whether any additional user groups were overlooked is not an action that the BA takes after finding that the number of concurrent users is a large portion of the target user group, which seems high, but an action that the BA takes to identify and evaluate the characteristics, needs, expectations, and influences of stakeholders. Conducting additional stakeholder analysis can help to discover and engage new or missed stakeholders.
Reference:
BABOK Guide v3, section 4.2: Elicitation
CCBA Exam Questions, question 30