Final answer:
In the context of CBC (Complete Blood Count), the reference ranges for interpreting results are typically what remain constant from year to year, not the actual values within an individual's blood test, as they can vary due to numerous factors.
Step-by-step explanation:
In biology, the term CBC stands for Complete Blood Count, a common blood test that measures various factors of a person's blood, including red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. However, the question appears to be asking about factors that remain constant from year to year within a CBC, which is unusual as many of these factors can vary due to health changes, medical conditions, or even normal physiological fluctuations. The only constituents of a CBC that could be interpreted as relatively constant would be the reference ranges used for interpreting the results, as these are established based on population averages and tend to remain consistent unless updated by new medical research or standards. It is important to note that individual patient values will typically vary within these reference ranges over time.