During creation of Exam_results table, you can add a constraint that validates the Mark to be valid:

a.

Create table Exam_results (Mark number(5,2) check (Mark between 0 and 100));

b.

Create table Exam_results (Mark number(5,2) check (Mark <= 0 or Mark >= 100));

c.

Create Exam_results (Mark number(5,2) check Mark>= 0 and Mark <= 100);

d.

Create table Exam_results (Mark number(5,2) check (Mark=> 0 and Mark =<100));