According to the reading, Smart Homes for Elderly Healthcare$-$Recent Advances and Research Challenges, examples of $Z_{?}$ research challenges for smart homes include $($select all that apply$)$:

privacy and security of the transmitted data

bottlenecks for the seamless and delay$-$less connectivity

integration issues among different devices

energy requirements of the devices

expansion capability of the system and interoperability among different smart home platforms

adoption of AI technologies in the computational platform of the smart home

designing a fully functional and comprehensive smart home that addresses all aspects such as home automation, monitoring of residents' health, safety and security, and home environment

there are no research challenges for smart homes

none of the above