The dot plots represent the distributions of values in data sets P and Q.

Data Set P has dots at 2, 3, 4, 5, 6.
Data Set Q has dots at 1, 2, 3, 4, 5, 6, 7.

Which of the following statements must be true?

I. The median of data set P is equal to the median of data set Q.

II. The standard deviation of data set P is equal to the standard deviation of data set Q.