The Grand Canyon, shown in the picture, took millions of years to to form. The Colorado River started this process by breaking down rocks. Which of the following also played a role in creating The Grand Canyon? please help i need to make a 100 A.

gravity

B.

erosion

C.

deposition

D.

weathering

Option A, Neither the researchers nor the study participants know who is receiving the drug and who is receiving the placebo.

Explanation:

In a double blind test, both the researcher and research participants are unaware of the exercise in a medical test . During the research active medication is given to some of the research participants making sure that researcher is unaware of that while observing all the participants. However, at the end of the experiment ,both the researcher and research participants get to know who has received the treatment.

Hence, option A is correct