Dr. Sullivan is conducting a clinical trial to determine if vitamin XX can improve test performance of students in an introductory college nutrition course. Dr. Sullivan puts all the students' names in a hat and draws names to determine if they will be placed in the control or the experimental group. The experimental group receives a capsule of vitamin XX and the control group a "sugar pill" that tastes and looks identical to the vitamin XX capsule. Neither Dr. Sullivan nor the participants know who is receiving which treatment. This experiment is BEST described as

double-blind, randomized, placebo controlled.

Explanation:

A double-blind experiment, often used in psychology research study, is a type of experiment in which both the participants and the researcher do not know who is receiving a particular treatment. This is to ensure that there is no bias in research results.

Hence, in this case, neitherDr. Sullivan nor the participants know who is receiving a particular treatment.

Randomized experiment is a type of experiment in which objects or individuals are randomly assigned to an experimental group. It is considered as the most reliable method of creating homogeneous treatment groups, so as to avoid biases or judgments.

Hence, in this case, Dr Sullivan randomly assigned students to both control and experimental group

Placebo-controlled experiment is the one used in testing a medical therapy, whereby there is a group that receives a sham "placebo" treatment which is specifically designed to have no real effect, aside the group of subjects that receives the treatment to be evaluated.

Hence, in this case, this is a placebo controlled experiment, as we have two distinct groups in control and experimental group.

Hence, this experiment can best be described as "double-blind, randomized, placebo controlled."

b) to encourage free trade

the answer is either c or d i think its d