Final answer:
The true statement about forgetting is that it helps to prevent unwanted information from interfering with necessary information, which is associated with interference theory.
Step-by-step explanation:
The true statement about forgetting from the options provided is that A. Forgetting helps keep unwanted and unnecessary information from interfering with retrieving necessary information. This process is part of interference theory, where proactive interference can hinder the recall of new information, and retroactive interference can impede the recall of old information.
For example, learning a new phone number may become difficult if the old number is still strongly remembered, and conversely, recalling the old number may become difficult after learning the new one. Other reasons for forgetting include encoding failure, where information is never stored in memory, and memory trace decay, where information fades over time. Importantly, forgetting is not predominantly about preventing the formation of general impressions or the potential for relearning material, as other options suggest.