Complex sentence: Bioterrorism is terrorism involving the intentional release or dissemination of biological agents (bacteria, viruses, or toxins), that may be in a naturally-occurring or in a human-modified form.
Split into simpler sentences: Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents are (bacteria, viruses, or toxins), and may be in a naturally-occurring or a human-modified form.