What Property of the Normal Curve Ensures That the Area

Multiple Choice

What property of the normal curve ensures that the area from the mean to -2 standard deviations is the same as the area from the mean to +2 standard deviations?

A) the least squares principle of the normal distribution
B) the skewness of the normal distribution
C) the symmetry of the normal distribution
D) the interval-ratio measurement of the normal distribution