The candidate will have to type his answer in the given box and once he submits it the answer is to be assesed by super computer understanding not only the language, syntex and grammer but also the subject in which the exam is held. Seems to be a thing like one shown in science fictions but could be a reality one day.
Only thing is if the purpose of assessing a student is complete with objective type test why to go for the other type with so many hassles.
Knowledge is power.
A blunt knife or rusted knife can't be useful for anything just for the sake we call it as the knife similar to PayTM series or Sachin or Virat records.
Let us say The answer is " Rama is a good boy". For computer evaluation you can give the keywords, are, is good boy. Answer written by the candidate is "Rama is not a good boy". But as far as the computer is concerned whatever keywords given to it are present in the answer. So he will get full marks. But the answer is negative to correct answer. A proper programme is to be planned and created. It will take a lot time to go for this computer valuation of descriptive answer.
Caution: Explosive. Handle with care.