Damping off is a common disease of seedlings that causes wilting and death of young plants. It is primarily caused by fungal pathogens that attack the roots and lower stems of seedlings. Option 1, Peronospola parasitica, is not responsible for damping off. It is a water mold that causes downy mildew on various plants. Option 2, Albugo Candida, is also not the cause of damping off. It is a pathogen that causes white rust on various plant species. Option 3, Phytophthora infestans, is responsible for causing late blight on tomatoes and potatoes but not damping off. Option 4, Pythium debaryanum, is the correct answer. This fungus-like pathogen causes damping off by attacking the seedlings` root systems.