I'm gonna go ahead and guess, and say its B.
Answer:
Percent Composition of 41K = 6.7302%
Explanation:
The explination is in the image.
With your mind. Boom. Lol I'm sorry I don't know I just need points
It is a trial aimed to reduce bias during an experiment. An example would be a sugar pill, something that has no real effect so that the results of the true trial can accurately be compared. Its like a control group.