Final answer:
In the Jaffe reaction used for measuring blood creatinine levels, the primary reagent component is picric acid.
Step-by-step explanation:
The primary reagent components used in the Jaffe reaction for measuring creatinine levels is c) Picric acid. The Jaffe reaction is a colorimetric method where creatinine reacts with picric acid in an alkaline medium to form a red-colored complex. The intensity of the color of this complex is directly proportional to the creatinine concentration in the sample and can be measured using a spectrophotometer. This method is widely used for the estimation of blood creatinine levels which helps in assessing kidney function.