Choose the sentence that 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.

I believe the answer is B. Structural adaptations are characteristics that change over time. Some animals adjust over the years to live better in their environments, and this is what it was talking about.

Elephants have long trunks to reach leaves they couldn't get to if their trunks were small. Same with the humming bird and the rose bush. They are adapting. However, the dog is only getting a drink. The dog can do that without having to adapt to anything.