Which of the following is the best term for the type of experiment described below? 50 people are randomly selected to participate in a clinical drug trials in which one half will receive the actual drug and the other half will receive a placebo. Neither the researchers conducting the experiment nor the subjects participating will know who receives switch

A. Randomized experiment

B. Controlled experiment

C. Biased Experiment

D. Double blind experiment

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.