While a diagram is not provided, we can generally visualize the relationship between musicians, instrumentalists, and violinists to derive a logical understanding for the explanation.

Musicians encompasses anyone who is involved in music creation. Instrumentalists are a subset of musicians as they create music through instruments, but not all musicians are instrumentalists (such as singers or composers). Violinists are an even narrower subset as they use a specific instrument, the violin, to create music. So, in a logical diagram, the broadest category, musicians, will be represented by the largest circle, containing all other categories. The next largest circle, instrumentalists, falls within the musician circle, but doesn`t fill it entirely. The smallest circle, violinists, falls entirely within the instrumentalists` circle, reflecting that all violinists are instrumentalists, and therefore, are also musicians.

Hence, the correct diagrammatic representation will follow the sequence – Musicians > Instrumentalists > Violinists.

If the given answer is not reflecting the above explanation, it could be incorrect. Make sure the diagram reflects the hierarchical relationship among the groups.