A. Group decision making, however, does not necessarily fully guard against arbitrariness and anarchy, for individual capriciousness can get substituted by collusion of group members.
B. Nature itself is an intricate system of checks and balances, meant to preserve the delicate balance between various environmental factors that affect our ecology.
C. In institutions also, there is a need to have in place a system of checks and balances which inhibits the concentration of power in only some individuals.
D. When human interventions after this delicate balance, the outcomes have been seen to be disastrous. (CAT 1999)
The best starting sentence is B and D is a continuation (this delicate balance) of sentence B. Look for the BD link. You can eliminate options (a) and (b). Between C and D, the better starting sentence is B (because if you notice option (c) "In institutions also,".- the "also" can never be part of a starting sentence) hence, answer is option (d)