question_answer 20)

  Ecotone is (a) a polluted area (b) the bottom of a lake (c)a zone of transition between two communities (d) a zone of developing community

Answer:

                  (c) The adjacent biotic (natural) communities generally do not posses a fine demarcation edge or line between them. The adjacent of two communities is represented by population of both the communities, and this transition zone between two communities is referred as eco tone. Rest of the options do not define eco tone (zone of transition).