Consider the following table EXAM$\_$RESULTS:

$\backslash$table$[[$STUDENT$\_$ID$,$FIRST$\_$NAME,LAST$\_$NAME,EXAM$\_$ID$,$EXAM$\_$SCORE$],[10,$LAURA,LYNCH$,1,90],[10,$LAURA,LYNCH$,2,85],[11,$GRACE,BROWN,$1,78],[11,$GRACE,BROWN,$2,72],[12,$JAY,JACKSON,$1,95],[12,$JAY,JACKSON,$2,92],[13,$WILLIAM,BISHOP,$1,70],[13,$WILLIAM,BISHOP,$2,100],[14,$CHARLES,PRADA,$2,85]]$

What is the result of the following SQL statement:

SELECT COUNT$($DISTINCT STUDENT$\_$

ID$)$ FROM EXAM$\_$RESULTS;

$3$

$5$

$6$

$4$