“考完试，总算了却一___心事。”
“Exam done — finally settled a ___ of worry.” Which measure word?
全球翻车率（内测预估）
✓桩
zhuāng · measure word for posts/piles
B颗
kē · measure word for small round things
C个
gè · generic measure word
D件
jiàn · measure word for matters/items
心事论“桩”，跟买卖和案子一个量词。心里的事，件件都是悬案。
桩 (“stake/case”) is the idiomatic measure word for weighty matters: 一桩心事, 一桩买卖, 一桩案子.