Which of the Following Is the Definition of a Standard

Which of the following is the definition of a standard deviation on the scores of an assessment?

A) It is the statistical measure of the degree by which the scoring distribution is spread amongst the test-takers
B) It is the statistical measure of how far from the norm a student is
C) It is the statistical measure of how a child's test taking scores deviate over the years
D) It is the statistical measure of how a child does on certain types of questions