Final answer:
Compiling a single user's online shopping activity from two separate databases is an example of cross-correlation of data, as it involves analyzing the relationship between two different but related data sets. The correct answer is option A.
Step-by-step explanation:
Among the given options, compiling a single user's online shopping activity that is stored in two separate databases, under two slightly different names, is an example of cross-correlation of data. Cross-correlation refers to the measure of the relationship between two different time series. In the context of user data, it would involve analyzing and comparing similar activities from different sources to find a pattern or relationship.
While compiling data of a single user might more closely resemble data matching or merging, it involves a form of temporal or spatial correlation if you are comparing user activities across time or systems. Therefore, this activity involves establishing a relationship between the two data sets (the two separate databases) that pertain to a single user's shopping behavior.