Which of the following techniques contrasts the current and desired business views to analyze possible business changes?

A major stakeholder of a project is surprised to learn that a particular requirement was not implemented during the latest launch. The business analyst tells the stakeholder that the requirement status was changed to
"deferred."
What could have prevented the stakeholder from being surpnsed about the status change?

A financial company deployed a new online product to their customers to invest in the stock market. The company notices a problem regarding financial calculations and starts the problem analysis. The company discovers that the new rules for taxes and fees were not implemented.
This problem could have been avoided by:

A business analyst is working on a highly complex project and has elicited a large number of requirements from stakeholders in several departments Due to the large number of requirements, the stakeholders have determined that they would like to prioritize them to minimize a potentially large scope.
Which technique could the business analyst use to manage requirements?

Which tool should be used to improve the communication of product needs with the stakeholders and to improve their understanding?