Answer- B
Reasoning: Since Eagles directly eat Thrush, their populations would decrease.
The other answers are wrong because with the first choice, Eagles would not increase in population if one of their food sources were removed. For the third choice, Dragonflies wouldn’t increase. Since Thrush eat Dragonflies, the disappearance of Thrush wouldn’t hurt the population of Dragonflies. Lastly, The last option is wrong because corn isn’t reliant on animals to survive. If Thrush disappear, corn will not be affected. This leaves B. to be the answer.