Even If Somewhat Impractical,which One of the Following Preanalytical Factors

Multiple Choice

Even if somewhat impractical,which one of the following preanalytical factors should be standardized when establishing a reference interval for an analyte?

A) Location (building,city,etc.) in which the venipuncture is performed
B) The method of specimen collection
C) Reagents used in analyte analysis
D) The specific method used for analysis