ESPP capital gain tax form for non residents

[caffeinatedskier]

I purchased and sold my company shares last year using ESPP (Employee Stock Purchase Program). I am a non-resident alien (F-1 visa, OPT).  What form do I need to report the capital gain from this sale (apart from the discount reported as income on my W-2)?

I have heard conflicting information on the subject: 

1. Option 1: Attach form 8489 as mentioned here: https://thefinancebuff.com/adjust-cost-basis-for-espp-sale-in-turbotax.html
2. Option 2 (endorsed by my Tax CPA 1):  Do nothing. Non residents are not subject to taxation of capital gains. Also, does this mean I will have to file a tax return in my home country too? His references: ref1, ref2
3. Option 3 (endorsed by my Tax CPA 2): Report it on 1040-NR Schedule NEC under "Capital Gains or Losses from Sales or Exchanges of Property".

What is my safest bet here and what is the worse that can happen if I go wrong? ( I really don't want to hire tax CPA #3 🙂 ).