Identify which of these designs is most appropriate for the given experiment: completely randomized design, randomized block design, or matched pairs design. currently, there is no approved vaccine for the prevention of infection by a certain virus. a clinical trial of a possible vaccine is being planned to include subjects treated with the vaccine while other subjects are given a placebo. the most appropriate is randomized block design. identify which of these designs is most appropriate for the given experiment: completely randomized design, randomized block design, or matched pairs design. currently, there is no approved vaccine for the prevention of infection by a certain virus. a clinical trial of a possible vaccine is being planned to include subjects treated with the vaccine while other subjects are given a placebo. the most appropriate design