Astudy was conducted to evaluate the impact of taking a nutritional supplement on a person's reaction time. one hundred volunteers were placed into one of three groups according to their athletic ability: low, moderate, or high. participants in each group were randomly assigned to take either the nutritional supplement or a placebo for six weeks. at the end of the six weeks, participants were given a coordination task. the reaction time in completing the task was recorded for each participant. the study compared the reaction times between those taking the supplement and those taking the placebo within each athletic ability level. which of the following is the best description of the study?
(a) a randomized block design
(b) a completely randomized design
(c) a matched-pairs design
(d) a randomized observational study
(e) a stratified observational study

a) a randomized block design.

Explanation:

The best description of this study is a randomized block design.

A randomized block design has the following procedure: The researcher first divides the sample into different subgroups called "blocks" where each block has similar characteristics (The block variability is less than the variability between blocks), then, the researcher applies different treatments to people in each block, the subjects within each block are selected at random to receive these different conditions.

In the example, the researchers first divided the volunteers into three groups according to their athletic ability (these would be the blocks) and then, they randomly were assigned a different treatment (supplement or placebo). Finally, they were assigned a task and observed the results. Therefore, it is an example of randomized block design. Thanks to how the study was made, it ensures less confounding variables.

people are just afraid of difference. honestly no where in the bible does it say you can't be gay or bi or anything it says he loves all his children the same and he wants the best for us but we need to be truthful and all that yadda yadda anyways, god doesn't hate gays, he does hate hate, hypocrites, liars, and all that and even then he forgives those who ask for it. so your mum's reasoning is totally wrong xd sorry love, i had to rant a bit but i hate it when people do that. if anything i accept you! stay amazing! ^-^

you aren't worthless, you are a one of a kind person who, deserves happiness like anyone else, you may not get it but everyone deserves happiness. i hope this .