(a) removal of 80% tigers from an area resulted in greatly increased growth of vegetation
(b)removal of most of the carnivores resulted in an increased population of deers
(c) the length of food chains is generally limited to 3 - 4 trophic levels due to energy loss
(d) the length of food chains may vary from 2 to 8 trophic levels
Which two of the above statements are correct ?
$\begin {array} {1 1} (1)\;a,b & \quad (2)\;b,c \\ (3)\;c,d & \quad (4)\;d,a \end {array}$
