The correct answer of this question is A.Inductive reasoning.
As per this question the ant was allowed to have the liquid which was repeated for all ants and it was concluded that the liquid is an ant poison.
Inductive reasoning is based on specific observation which are used for making generalized statement or hypothesis which ultimately gives the conclusion. In the given question, specific example is stated which is giving the conclusion that liquid is an ant poison.Thus, this approach of reasoning is considered as inductive reasoning .