Direction: The following question consists of two sentences with one blank only. You are given seven words as answer choices. From the given options you have to select the one which will complete the given sentence.

There is a wide scope to use rainwater harvesting technique to conserve _________ water resource. It can be done by harvesting rainwater on rooftop and open spaces.

i) Congenial

ii) Precarious

iii) Precious 

iv) Circumstantial 

v) Exhaustive

vi) Contrived

vii) Invaluable