This core concept refers to defining the solution options and recommending a solution that is most likely to meet the business needs as well as have the most value.  

Let's look at an example to bring this concept around solution into the real world.

The needs identified during the payroll calculation automation initiative clearly align with a solution where the payroll calculation is outsourced rather than kept in-house. The needs are to reduce internal operating costs and reduce calculation errors caused by internal manual procedures. The best solution recommendation based on these needs would be to outsource the payroll calculation function. This will yield the best value for money as well as adhering to the need to reduce errors caused by cumbersome internal processes.

This example illustrates how the core concept of solution can be implemented during Requirements Analysis and Design Definition with a focus on providing solution options that meet the needs and maximize the value.