This question was very popular among the candidates.  However, it was poorly attempted.  Majority of the candidates defined elastic limit by referring to it as a point.

The expected answers are:

 Elastic Limit:
The minimum stress/force applied on an elastic material beyond which a permanent deformation occurs.
                                                                                   
Yield Point
The point on a stress/strain or load/extension graph beyond which the elasticmaterial becomes plastic.