Final answer:
The subject of this question is English. The given options refer to something or someone that is completely dead or unusable.
Step-by-step explanation:
The subject of this question is English. The given options 'deceased,' 'non-viable,' 'irreparable,' and 'non-functional' all refer to something or someone that is completely dead or unusable. These words belong to the vocabulary of the English language, specifically related to the concept of death or non-functionality. In English, we use these terms to describe things or individuals that have ceased to function or no longer exist.