When There Are $\infty$ Degrees of Freedom, The $t _ { \infty }$

When there are $\infty$ degrees of freedom, the $t _ { \infty }$ distribution

A) can no longer be calculated.
B) equals the standard normal distribution.
C) has a bell shape similar to that of the normal distribution, but with "fatter" tails.
D) equals the $\chi _ { \infty } ^ { 2 }$ distribution.