The correct answer is D.
The domain is the broadest category in the classification of living organisms. All the living organisms are placed in three domains, which are archaea, bacteria and eukaryotes. The prokaryotes are separated into two groups, that is archaea and bacterial based on the differences in their 16S rRNA genes. Amoeba is classified as an eukaryotes because, its cell is more developed than that of bacteria.
An icon is a symbolic representation of an action to be taken, given in emails or message bars. Icons are metaphorical representations of emotions and feelings which a human is unable to explain in words.
The icon used to represent an attachment is paper clip.
When we click this paper clip icon, it allows us to attach any file including a document or a picture in that particular email. An attachment may also contain a virus, Trojans, worms and other form of malware.