For a meaningful structural analysis, at least one load and one boundary condition is required. The "Supports" tab consists of all the available boundary conditions that are required to constrain the model. Generally, one of these support options is mandatory for producing stresses:
However, the most suitable minimal constraint (one among the various support types) depends on the loads that are being applied. If you can please elaborate a bit more about your requirement/application, I will be in a position to provide a better suggestion.
Thanks & Regards,