In a clade, mammalian has the three descendents: monotreme, marsupials, and eutheria. what will these three descendents together be called?

The correct answer will be- sister group or crown group.

Explanation:

A clade is the group of the organism which has descended from a common ancestor.  The visual representation of clade is known as a cladogram which shows the relationship between organism in tree-form.

In the visual representation, when two branches appear growing from a common branch, the two branches will be called "sister groups or crown groups".

Since three mammalian namely monotreme, marsupials, and Eutheria are thought to have descended from a common ancestor of mammals, therefore, they will be called "sister groups".

Thus, the sister group or crown group is the correct answer.

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