While instructing a patient about antibiotic therapy, the nurse explains to the patient that bacterial resistance to antibiotics can occur when: 

A. Neutrophils: Neutrophils are a type of white blood cell that plays a key role in the immune system's response to infections, particularly bacterial infections. They are not primarily involved in eliminating cancer cells.

B. Eosinophils: Eosinophils are another type of white blood cell. They are important in the immune response to parasites and are also involved in allergic reactions. While they have a role in the immune system, they are not the primary cells involved in eliminating cancer cells.

C. Platelets: Platelets, also known as thrombocytes, are not cells but rather small cell fragments. They are essential for blood clotting and do not directly participate in the immune response against cancer cells.

D. Macrophages: Macrophages are a type of white blood cell that are involved in the immune system's defense against cancer. They are phagocytes, which means they engulf and digest cellular debris, foreign substances, and cancer cells. Macrophages play a crucial role in the body's immune surveillance and response against cancer.

A. Delayed hypersensitivity reaction: This type of hypersensitivity reaction, also known as Type IV hypersensitivity, involves a delayed response by the immune system and is mediated by T cells. It does not necessarily involve a failure of self-tolerance.

B. Antibody-mediated reaction: This type of hypersensitivity reaction, also known as Type II hypersensitivity, involves antibodies targeting specific antigens on cell surfaces, leading to cell destruction. It doesn't directly indicate a failure of self-tolerance but rather an immune response against specific cells or tissues.

C. Autoimmune reaction: In autoimmune reactions, the immune system fails to recognize certain body tissues or substances as "self," leading to an immune response against the body's own cells or tissues. This results from a breakdown in self-tolerance, where the immune system mistakenly targets its own body.

D. Immediate hypersensitivity reaction: This type of hypersensitivity reaction, also known as Type I hypersensitivity, involves an immediate response by the immune system to an allergen. It includes conditions like allergies and anaphylaxis, where the immune system reacts strongly to substances that are normally harmless. This response does not necessarily indicate a failure of self-tolerance but rather an exaggerated response to specific antigens.