All living things are either eukarya, bacteria, or archaea. these three broadest categories in the classification of life are called
a. domains
b. kingdoms
c. orders
d. species

These are called: domains.

Because they are three, this is also called the Three-Domain System, which was introduced by Carl Woese. The Archaea and Eukaryota are more closely related, Bacteria being more distant from the two.

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