Questions

District Judges in a state are appointed by the Governor of the State.

The given sentence is in simple present tense and states a general fact, hence the latter half of the sentence with the blank will also be in the simple present tense. Since the subject in the latter part of the sentence is singular .i.e. 'the number', the verb will be followed accordingly. Hence, option 4 is the correct answer.

Biosphere Reserves are established for the conservation of biodiversity for economic and social development  and  maintenance  of associated  cultural  values.There are  18  Biosphere  Reserves  in  the country.  Agasthyamala  Biosphere reserve is located at the southern-most  part  of  the  Western  Ghats and spread over two states,Kerala and Tamil Nadu. It was established in 2001;Nokrek Biosphere Reserve is  a  national  park  situated  in  West Garo  Hills  district  of  Meghalaya. UNESCO   made   it   the   Biosphere Reserves  in  May  2009;The  Great Nicobar   Biosphere   Reserve   has such    ecosystems    that    include tropical   wet   evergreen   forests, mountain    ranges    and    coastal plains. The region is well known for its rich biodiversity. It was made a biosphere reserve in January 1989; while  The  Great  Himalayan  is  a National   Park   situated   in   Kullu region  of  Himachal  Pradesh.  The park was established in 198