Final answer:
The correct option is b) retrieval. The inability to retrieve previously known information is likely due to a failure in the retrieval process, one of the three main functions of memory alongside encoding and storage.
Step-by-step explanation:
If you find yourself unable to retrieve information that you originally knew, it is likely because your retrieval process failed. In psychology, there are three main functions of memory: encoding, storage, and retrieval. Encoding is the input of information into the memory system, storage is the retention of the encoded information, and retrieval is getting the information out of memory storage and back into conscious awareness. Without successful retrieval, the stored information despite being available in memory becomes inaccessible at the moment you are trying to recall it.
Common issues with retrieval may include interferences such as retroactive interference, where new learning hampers memory of previously learned material, or it might be simple forgetfulness. The potential for failure at the retrieval stage highlights the importance of effortful processing and proper memory enhancing strategies when learning new information.