Consider the following schema $$

STUDENTS$($student$\_$code, first$\_$name, last$\_$name, email,

phone$\_$no$,$ date$\_$of$\_$birth, honours$\_$subject, percentage$\_$of$\_$marks$)$;

Which of the following query would display names of all the students whose email ids are entered but left blank?

Group of answer choices

select first$\_$name, last name from students where email $=0$;

select first$\_$name, last name from students where email IS NULL;

select first$\_$name, last name from students where email $=$;

select first$\_$name, last name from students where email $=$NULL$$;