Passage Summary: Scientists believe vitamin C is vital for making collagen, a protein found in our bones and tissues, which leads some doctors to use it for treating certain sicknesses.

Reasoning: Vitamin C is essential for the production and maintenance of collagen, which is a protein found almost exclusively in bones and connective tissue.

Analysis: Since this is a 'Most Strongly Supported' question, we must treat the premises as absolute facts and find the most logical inference. The stimulus connects vitamin C to collagen and collagen to bones and connective tissue, then mentions doctors using vitamin C for 'common illnesses.' A strong inference would likely connect those illnesses back to the tissues where collagen is found. Look for an answer that suggests these illnesses involve the bones or connective tissues that rely on vitamin C for maintenance.