Correct Option (D)
The passage explicitly states, "we have lost the fullness of the joy of giving, and with it the fullness of the joy of receiving." This indicates the author's primary concern is with the incomplete experience of joy in these acts. The central theme revolves around the diminished capacity of adults to experience happiness fully, contrasting with children's "clear and complete" joys.
Incorrect Options:
Option (A): The passage notes that children "do not look too forward nor too far backward," implying a contrast with adults who might. While the author suggests that "some of our cares would shrink if we thought less about them," this is presented as a potential benefit rather than a direct statement of being "against" worrying about the past and future. The primary emphasis is on the loss of complete joy, not solely on the act of worrying about time.
Option (B): The passage discusses the diminished thrill of presents for adults, stating, "If presents bring less thrill now that we are grown up, perhaps it is because we have too much already; or perhaps it is because we have lost the fullness of the joy of giving, and with it the fullness of the joy of receiving." The author is not against thinking about the present itself, but rather against the lack of complete joy associated with present experiences, particularly giving and receiving.
Option (C): The passage begins by observing that "presents bring less thrill now that we are grown up." This observation is a symptom of a larger issue: the loss of "the fullness of the joy of giving, and with it the fullness of the joy of receiving." The author's concern is not merely the absence of thrill from new things, but the underlying cautious, anxious, and skeptical mindset that prevents a "single minded enjoyment into the happiness that come our way." The broader argument is about the capacity for complete joy, not a mandate for constant thrill.