Suppose you want to calculate how far each student was from the mean in exam 1 and store it in a column called deviation. Which of the following is a correct way to do so?单项选择题

A

grades$deviation <- mean(grades$exam1)

B

grades$exam1 <- mean(grades$exam1)

C

grades$exam1 <- mean(grades$exam1) - grades$exam1

D

grades$deviation <- grades$exam1 - mean(grades$exam1)

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