Which command creates a solid body between multiple cross-section sketches?

The command that creates a solid body between multiple cross-section sketches is the Loft command. Lofting is specifically designed to connect two or more profiles (cross-section sketches) to form a smooth transition between them. This is particularly useful in creating complex shapes such as freeform surfaces, where the geometry needs to follow the contours of the defined sketches.

When you use the Loft command, you select the starting and ending sketches, along with any intermediate profiles, and the software generates a solid body that smoothly adjusts between the shapes. This functionality allows for greater design flexibility compared to other commands.

For comparison, the other options serve different purposes. The Merge command combines existing solid bodies into a single body but does not create new bodies between sketches. The Extrude command generates a solid from a single sketch by extending it in one direction, and the Sweep command creates a solid by moving a profile along a predetermined path. These functionalities do not involve connecting multiple sketches like the Loft command does, making Loft the correct answer for this question.