[经] transaction at buyer's option

yoú mǎi fāng xuǎn zé de jiāo yì ㄧㄡˊ ㄇㄞˇ ㄈㄤ ㄒㄩㄢˇ ㄗㄜˊ ㄉㄜ˙ ㄐㄧㄠ ㄧˋ