Please choose the correct answer to the question: A young boy is reprimanded by his mother for sleeping with his heavy blankets over his head. His mother is worried that if the boy continues to sleep like that, he will suffocate. This is because

Answer1: beds can cause issues with breathing Answer2: breathing at night is deadly Answer3: CO2 in large amounts is fatal Answer4: CO2 can be ambivalent

Answer format: answer1/answer2/answer3/answer4
Answer: answer3