South Korea's largest mobile phone operator is to offer users a new service that it says will repel mosquitoes and subscribers can download a sound wave that is______to human ears but annoys mosquitoes within a range of about a metre.
【正确答案】 D
【答案解析】解析：句意：韩国最大的手机经营商即将向消费者提供一项新的服务——驱除蚊子，订阅者可以下载一种声波，这种声波人类听不到但是可以驱逐附近一米范围内的蚊子。inaudible是形容词，意为“听不见的"，符合句意。因此D选项正确。