956: What is the correct sequence of the following Indian states in descending order of their length of surface roads per 100 km. sq. of their area ?
I. Haryana
II. Maharashtra
III. Punjab
IV. Tamil Nadu
Select the correct answer using the codes given below :
Codes :
(a) IV, II, III, I
(b) IV, III, I, II
(c) III, IV, I, II
(d) III, IV, II, I
960: Within biological communities, some species are important in determining the ability of a large number of other species to persist in the community. Such species are called
(a) Keystone species
(b) Allopatric species
(c) Sympatric species
(d) Threatened species