3dimensional information in IOPAs can be taken by:: (A) Examining 2 films projected at right angle to each other, (B) Examining 2 films projected at different angles, (C) CLARK rule, (D) All of the above
Answer is D. Image in a X-ray is a dimensional information. To exactly locate the position of an object a three dimensional information is necessary. To obtain this 2 methods can be used

examining two films projected at right angles to each other.
examining  two films projected at different angles called as CLARK Rule (or) Buccal object rule (or) Tube shift metro or LOB rule.