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

These three descendants together would be called sister groups.

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The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.