Select the experiments that use a completely randomized design. a. To test an epidermal treatment on fish in polluted stream water, 50 fish with epidermal abrasions from the same stream are randomly placed into two aquariums. One aquarium receives the epidermal treatment, and the other receives no treatment. b. Scientists assign the plants on the outer edge of a garden to an old fertilizer and plants in the middle of the garden to a new fertilizer. At the end of one month, the scientists randomly select four plants from each group to measure growth and determine the results of the study. c. Participants in a study to determine the effects of a new blood-pressure remedy are divided into groups based on gender, and each subject in each group is randomly assigned to receive the new remedy, an existing remedy, or a placebo. d. In a dermatology study designed to test whether a new supplement helps individuals increase skin firmness, a computer randomly assigns participants into a group receiving the supplement and a group receiving an inactive pill. e. A computer scientist is testing new antivirus software on computers that were built in the last month. Ten computers with operating system A were randomly selected, and ten were chosen with operating system B. Five computers with each operating system were randomly assigned to be scanned with the new software, five to the existing software.