It's depend on the question! But anyway it's not necessary have to put because you only have to write only limited words which is 50-80 words. If you write introduction you can't write the point. But better start with only short introduction if you want and start to the point. In my last exam, I wrote introduction but I can't write the point so I also can't limit my words so I lost my marks. I got 11/15 in my section B.