Because of
Used to express cause or reason for something, often found in notices or formal documents.
Examples
事故のため、バスは運休します。
Due to an accident, the bus service is suspended.
この商品は人気につき、売り切れです。
This product is sold out due to high demand.
出席につき、予約が必要です。
Reservations are required because of attendance.
Quick check
この商品は人気___、売り切れです。