Understanding your situation, you're concerned about your eligibility to take the NEET exam after completing your 12th PCM from the RBSE board and obtaining additional biology from the RSOS Open Board.

To determine your eligibility, we need to consider a few factors:

• NCC (National Council of Educational Research and Training) regulations: NCC requires candidates to have passed Physics, Chemistry, and Biology in Class 12 to be eligible for NEET.
• RSOS Open Board certificate validity: It's essential to check if the additional biology certificate from RSOS Open Board is recognized for NEET.
• State board regulations: Your state's education board might have specific eligibility criteria for NEET.

Here's what you should do:

• Review NCC guidelines: Visit the NCC website to understand the exact eligibility criteria for NEET.
• Contact RSOS Open Board: Inquire about the validity of their additional biology certificate for NEET.
• Check state board rules: Contact your state's education board to clarify any specific requirements.

Generally, if the RSOS Open Board certificate is valid and you meet all other eligibility criteria, you should be able to apply for NEET.

Remember that NEET eligibility rules can change, so always check the latest information on official websites.

I recommend resolving this matter as soon as possible to avoid any potential delays in your NEET preparation.

hope this helps you!!