The answer would be plant. There is a kingdom called plantae, where all plant-like organisms fall, which means tree is under it. Birds and humans are under another kingdom called Animalia.
It’s B. I did research and found that it’s the application of scientific knowledge for practical purposes.
D makes the most sense, the rest of them aren’t really logical.
A heterogeneous mixture composes of non- uniform components, so the concrete would be the answer, because you can tell the components from one another.