What defines the concept of 'minimal risk' in research according to 21 CFR 56.102(i)?

The concept of 'minimal risk' in research, as defined by 21 CFR 56.102(i), means that the risks involved in the research should not be greater than risks encountered in daily life. Options A, B, and D are incorrect because they are more narrow in their definition of minimal risk. Option A states that there should be no risk at all, which is not an accurate definition according to 21 CFR 56.102(i). Option B focuses solely on financial risk, while option D only considers psychological risk. However, the concept of minimal risk encompasses all potential risks, including physical, social, psychological, and financial, and thus option C is the most appropriate answer.