A(n) refers to a substance or treatment that is often used in an experiment but does not have an actual medicinal or experimental benefit. a. extraneous variable b. placebo c. confounding variable d. independent control  

Scientists follow specific processes in order to determine valid explanations and conclusions from observations. david observed strange lights in the sky above his home outside of roswell, new mexico. the only explanation that makes sense to him is that there are ufos in the area. what should david do next to verify his explanation?