Explanation:
The dog salivating is an example of responding to stimuli
Answer: Option D. Vestigial trait
Explanation:
Vestigial traits simply involves those traits (such as organs, structurrs or behaviors) which are found or occurs in organisms or animals, that have lost all or most of their original function through evolution. These vestigial structures were organs that performed some important functions in the organism at one point in the past. In most cases, organs or traits once identified as vestigial simply had an unrecognized function.
Polymerase chain reaction to amplify the DNA would be the technique used in the blood lab.
The answer would be sewer systems.