Considering the situation described in the question, the memory concept that best explains why Rachel falsely encoded the books and failed to encode the skull is known as Schema.
Schema as a memory concept is a semantic memory structure that assists in arranging the new information humans encode.
Schema is known to assist individuals in modifying fractions and chunks of memories that have been overlooked, thereby falsely encoding some information and failing to encode others.
Hence, in this case, it is concluded that the correct answer is Schema.
Learn more about Schema here: https://brainly.com/question/8793777