Behavioural Targeting, the Practice of ________, Is Being Used by More

Behavioural targeting, the practice of ________, is being used by more and more companies.

A) tracking customers' activities and rewarding customer loyalty
B) managing customer relationships
C) mining and analyzing data from data warehouses
D) tracking consumers' online movements and using this information to target ads to them
E) observing and interacting with consumers in their natural environments