Answer: They aren't classified as birds because monotremes are mammals, unlike birds. They are referred to as mammals because they have mammary glands responsible for manufacturing and producing milk. Birds cannot do this.
<span> it makes a tissue: a group of similar cells that work together to perform a specific job in the body.</span>
I think it's (c). Evidence suggests they were the first plants
Explanation
Evidence shows that plants evolved from freshwater green algae, a protist
There's similarities between green algae and plants .both plants and green algae contain the same form of chlorophyll.
but land plant are multicellular and autotrophic
