Final answer:
The gatekeeper is the role in the household purchase process that controls information flow.
Step-by-step explanation:
The role in the household purchase process that involves controlling information flow into the household is A) A gatekeeper.
The gatekeeper is responsible for controlling the information that enters the household, such as marketing messages, advertisements, and product recommendations. They may filter out certain information or influence the purchasing decisions based on what they perceive as important or relevant.