Passage:
Passage-II It is possible to give wedding presents, birthday and Christmas presents, without any thought of affection at all, they can be ordered by postcard; but the unbirthday present demands the nicest care. It is therefore the best of all, and it is the only kind to which the golden rule o f present-giving imperatively applies - the golden rule which insists that you must never give to another person anything that you would not rather keep: nothing that does not cost you a pang to part from. It would be better if this rule governed the choice also of those other three varieties of gifts, but they can be less exacting.
‘They can be ordered by postcard’ means that
- Athe present may only be a postcard
- Bthe present would be an expensive one
- Cthe choice does not involve much care
- Dthe present would not be worth giving
Explanation
The phrase 'ordered by postcard' illustrates that wedding, birthday, and Christmas presents can be chosen with no thought or effort — a postcard order is the ultimate low-effort purchase. The author's point is that such gifts may involve no affection or care, unlike the unbirthday present. It does not mean the gift is literally a postcard, or that it is expensive or worthless. Hence the phrase means the choice does not involve much care, option (C).