Cancer

Let's analyze each statement: A. "Computed tomography and magnetic resonance imaging detect cancers of internal organs" is true. These imaging techniques are used for detecting tumors and abnormalities in internal organs.
B. "Chemotherapeutic drugs are used to kill non-cancerous cells" is incorrect. Chemotherapeutic drugs primarily target cancerous cells, though they may also affect healthy cells.
C. " -interferon activates the cancer patients' immune system and helps in destroying the tumour" is correct. -interferon enhances immune responses against cancer cells.
D. "Chemotherapeutic drugs are biological response modifiers" is true. They help modify the biological response to cancer by affecting the immune system or other mechanisms.
E. "In the case of leukemia, blood cell counts are decreased" is true. Leukemia affects the production of blood cells, leading to a decrease in the number of white blood cells, red blood cells, or platelets. Thus, the correct answer is C and D only.