OK, here's how it works - they're asking whether you want to withdraw your application if the sponsor is not eligible . . . normally we recommend that you say, "Yes" - that you want to withdraw the ap. The reason for this is that, without an eligible sponsor, the application is dead in the water anyway. No point in it being forwarded to the visa office so that you can wait for months and months for it to finally be refused due to an ineligible sponsor.
It's better to withdraw and have the file sent back to you right away so that you can work on correcting whatever issue is making the sponsor ineligible, and then you reapply.