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  

A(n) B. Placebo refers to a substance or treatment that is often used in an experiment but does not have an actual medicinal or experimental benefit.

The "Placebo" is a type of "Medicine" that does not actually contain medicine, and is used to trick the users mind into solving the problem they have.

Answermuch larger;

Answerthe global climate during the paleogene departed from the hot and humid conditions of the late mesozoic era and began a cooling and drying trend which dispite having been periodically disrupted by warm periods such as the paleocene-eocene thermal maximum, persists today;