There are many correct ways to prioritize one's work, but it is important for the candidate to demonstrate that they will consider the impact as well as the difficulty of projects when prioritizing their work. It is important to remember that workplace safety ALWAYS takes precedent to other items. Assuming there are no pertinent safety projects, then tasks should be prioritized based on impact, cost, and lead-time. There is no magic formula, the engineer just needs to justify their thinking in a reasonable way. For example a project with a relatively small business impact that carriers no cost and that can be implemented on the same day, may be prioritized ahead of a large impact project that takes weeks to complete. It is also important to remember the impact of team-member morale and buy-in. A project with a difficult to measure business impact that will improve the rapport with the team and lead to additional idea generation may be prioritized ahead of other items with a more measurable effect.