Correct Answer & Explanation
Option C
• The sentence talks about a lack of vitamin C. 'Deficient' means not having enough of a specified quality or ingredient; lacking.
• 'Defray' means to pay expenses.
• 'Defile' means to make something dirty or impure.
• 'Defer' means to postpone.
• 'Default' means failure to fulfill an obligation.
• Thus, 'Deficient' is the most suitable word.