Final answer:
The most accurate example of harmful bacteria is pathogenic bacteria causing diseases, as they can produce toxins, lead to infections, and result in serious illnesses, contrasting with other beneficial bacteria roles.
Step-by-step explanation:
The best example of how some bacteria can be pathogenic and detrimental to the health of living organisms is C) Pathogenic bacteria causing a disease. This is because pathogenic bacteria invade the body, often producing toxins or causing infections that can lead to diseases such as tetanus, diphtheria, pertussis, tuberculosis, and leprosy.
While many bacteria are beneficial, playing vital roles in nutrient cycling like nitrogen fixation, or by forming symbiotic relationships with other organisms, some are harmful. Harmful bacteria can contaminate food leading to foodborne diseases, or become resistant to antibiotics, making them difficult to treat. Furthermore, they can be utilized in biological weapons, showcasing their potential for causing significant health issues.
These pathogenic bacteria are a classification of heterotrophs that require energy and carbon from other organisms, and in this unfriendly relationship, they consume host tissues as food, often resulting in illness for the host. Understanding the dual nature of bacteria—beneficial and harmful—is crucial for managing health and disease.