Which of the following steps involves figuring out which user problems are most important to solve?

The step that involves figuring out which user problems are most important to solve is centered around specifying the user's needs. This phase is critical because it requires gathering and analyzing data about users to identify their primary pain points, challenges, and desires. By understanding what users need most, designers can prioritize issues that will have the greatest impact, ensuring that solutions developed will effectively address the most pressing concerns.

This step typically involves empathy-building techniques like user interviews, surveys, and observation to gain insights into user experiences. The focus is on distilling this information into actionable insights, so that the design process aligns closely with real user needs. Identifying and specifying these needs lays the foundation for subsequent stages, where designers can create targeted solutions to the problems at hand.

In contrast, the other options involve different aspects of the design process. Understanding user experiences focuses on gathering data about how users interact with a product, while designing solutions and prototyping the designs are more about generating and testing ideas based on established user needs rather than determining what those needs are.