Which sentence does not describe a structural adaptation?

a.
an elephant has a long trunk that it uses to reach leaves high in a tree.

b.
a dog walks to a stream and drinks when it gets thirsty.

c.
a hummingbird has a long, thin beak to sip nectar from flowers.

d.
a rosebush has thorns to protect it from animals that might eat it.

The diagram below represents a marine food web and a process that can harm the human population. each circle represents an organism and the smaller dots inside them represent a toxic substance. what is being represented and how does it harm the population? the diagram represents biological half-life, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents biomagnification, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents the process by which different organisms prey upon each other; this can impact the human population by reducing the number of organisms that do not contain the toxin. the diagram represents the way that toxins are metabolized by living organisms, with those at greater trophic levels able to metabolize more efficiently than those at lower levels. this means that those at higher tropic levels are safer for humans to consume compared to the organisms at lower trophic levels.

What is the difference between how ionic and covalent bonds form

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?