第一次發文，懇請大家協助解答~
以下是BBC某篇新聞的節錄，想知道的是"in which..."
這邊的in是跟哪個字相關呢？
Crownstone is promoting a system in which a home's lights and
plug sockets automatically react to a resident's presence
based on them having a Bluetooth-broadcasting wearable or smartphone on them,
rather than waiting to be given a command.
感謝~