For my application, I selected "1- Exemption from Labour Market Impact Assessment"
But I also remember getting confused about that. Regardless make sure you include an explanation letter, stating that you are SUV applicant, attach your letter of support and indicate and attach documentation that shows you meet the SUV work permit requirements (i.e you paid the employer compliance fee, state your LMIA Exempt No., proof of funds, company registration docs / ownership, etc)
Assume the immigration officers don't know anything about you or even the SUV program. Your job should be to hold their hand and clearly show, explain and direct their attention to the important stuff (how you meet eligibility requirements)
Believe me, through GCMS notes, some IRCC officers are still confused about the SUV program, how to code our work permits, and it is also clear from the SUV work permit application guide, that the instructions haven't been updated in a while.
And the fact that the option "2- Start-up Business class" isn't documented in the SUV work permit guide is sign of how IRCC hasn't maintained the application procedure for the SUV applicants.