閱讀下文，回答第30－33題

A growing number of people have chosen to wear smartwatches in recent years. The role of smartwatches has been evolving from simple 30 to multifunctional wearables. These devices offer wearers such features as fitness tracking, heart rate monitoring, notification alerts, and even smartphone integration. However, the limited battery life of smartwatches 31 , thus making scientists start to discover innovative power solutions like sweat harvesting or sweat collection（汗水採集）. They have adopted energy harvesting technology and explored the potential of sweat as an energy source for smartwatches. In the case of sweat-powered smartwatches, the energy is collected from the sweat 32 the human body during physical activities. Human sweat contains small amounts of chemical compounds and ions that can be converted into usable 33 . Early models and experimental devices have been developed, focusing on efficient sweat collection and the integration of energy-harvesting modules into the watch's design.

30.
(A)household goods

(B)filmmaking apps

(C)bluetooth headsets

(D)timekeeping devices