Answer: The strategy that Collins should adopt to maintain his privacy is D) establishing his personal boundary.
Step-by-step explanation: A personal boundary is the limit that a person sets in order to control the way in which other individuals might behave towards him/her. In that way, personal boundaries are related to a person's opinions, feelings, likes and dislikes. Taking this into account, establishing a personal boundary would help Collins to maintain his privacy and to control Stacey's desire.