Which command would best help in visualizing the internal structure of a complex assembly?

The Section View command is particularly effective for visualizing the internal structure of a complex assembly. This functionality allows users to create a "cut" through the assembly, revealing its components and how they interact within the overall design. By slicing through the assembly at a specified plane, you can see hidden components, understand the spatial relationships, and get a clearer picture of how different parts fit together. This is essential in assembly design, where understanding the internal configuration is crucial for troubleshooting, modifications, and ensuring proper assembly.

The other options, while useful in their own right, do not offer the same level of insight into the internal workings of an assembly. For instance, Isolate Components focuses on highlighting specific parts by hiding all others, which can help in examining an individual component but does not provide the comprehensive view of internal structures. The Measure Tool provides dimensions and distances, which is great for accuracy but does not convey the arrangement of components within an assembly. Details Highlight may draw attention to certain features or details, but again, it does not reveal the internal structure as effectively as a Section View does.