The Student T Distribution Is

The Student t distribution is

A) the distribution of the sum of m squared independent standard normal random variables.
B) the distribution of a random variable with a chi-squared distribution with m degrees of freedom, divided by m.
C) always well approximated by the standard normal distribution.
D) the distribution of the ratio of a standard normal random variable, divided by the square root of an independently distributed chi-squared random variable with m degrees of freedom divided by m.