Final answer:
Encoding is the process of inputting information into the memory system, and not being able to observe encoding makes it harder to pick up on one's mistakes (C). Attention and active processing are required for proper encoding. Without this, the information will not be stored in long-term memory and cannot be retrieved later.
Step-by-step explanation:
Since encoding is not observable, it is harder to pick up on your mistakes (C). Encoding is the input of information into the memory system. When this process is unsuccessful, it is known as encoding failure. This is akin to attempting to locate a book on your e-reader that was never downloaded. For memory to be reliable, we must engage in effortful encoding, which requires attention to detail and active information processing. Without proper encoding, information cannot be retrieved because it was never properly stored in long-term memory in the first place.
Encoding failure often occurs because we do not pay sufficient attention or we do not engage in effortful processing of the details. This can lead to difficulties in monitoring our learning progress. While we can make some observations externally, internal processes like encoding are invisible to us and therefore, our mistakes in encoding are harder to recognize and correct.