Researchers have long studied human memory. In a classic series of studies, the German psychologist Hermann Ebbinghaus investigated the storage and recall of information in memory. Based on his findings, he developed the so-called forgetting curve, a way of illustrating the rate at which people forget the information they have learned. The forgetting curve has been studied in a variety of different environments and for a variety of different stimuli. On day 1 of the memory research study, participants were asked to learn a list of items. Researchers then tracked the proportion of the list that the participants remembered as time passed. On day 2, some participants were asked to relearn the list. Again, the proportion remembered was tracked over time. On day 3, some participants were asked to relearn the list a second time, and the proportion they remembered was tracked over time. On day 4, some participants were asked to relearn the list a third time, and the proportion they remembered was tracked over time. The data from this study produced the following set of forgetting curves. Each line represents the memory of the learned or relearned list. The proportion of the list remembered is shown on the y-axis (memory), and the time interval for forgetting is shown on the x-axis (time remembered in days). <image 1> Based on the graph, which of the following statements BEST characterizes forgetting?

(A) Most forgetting occurs gradually over a long period of time.

(B) Most forgetting occurs after only a few days.

(C) Most forgetting occurs soon after information is learned.

(D) Most forgetting occurs at a constant rate over time.

Answer with the option's letter from the given choices directly. No punctuation.