Please choose the correct answer to the question: Which concept supports the endosymbiotic origin of complex, eukaryotic double-membrane structures?

Answer1: Mitochondria and chloroplasts arise from preexisting mitochondria and chloroplasts. Answer2: Mitochondria and chloroplasts arise from preexisting endomembrane systems. Answer3: Mitochondria and chloroplasts are synthesized in the nucleus. Answer4: Mitochondria and chloroplasts are synthesized in ribosomes.

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