D I believe, that sounds about right
<span>The question is asking "What is the main function of structural adaptations?" and the best answer is that A. They help the organism survive in its environment. Basically this is what drives the evolution the most - traces that help the organism survive in its environment are being promoted, and the offspring with those traces has the best chance for survival. </span>
so you wont get hurt while doing something
B. Protistans, a group thought to have given rise to other eukaryotic cells
They are further classified into: fish, amphibians, birds, reptiles and mammals.
I hope I've helped : )
