Match List-I with List-II:

Choose the correct answer from the options given below:

List–I (Type of Interaction)	List–II (General Nature of Interaction)

(A) Parasitism

(I) Species A benefits while species B remains unaffected

(B) Mutualism

(II) Both species A and B negatively affected in the interaction

(C) Commensalism

(III) Species A generally smaller than species B

(D) Competition

(IV) Both species A and B positively affected in a positive and obligatory interaction

Correct option is B

Introduction

Species interactions are a central concept in ecology. These interactions—such as parasitism, mutualism, commensalism, and competition—define how species coexist and impact each other's survival and fitness.

Information Booster:

Based on ecological principles, here is the correct matching between the types of interaction (List-I) and their general nature (List-II):

• (A) Parasitism$$\rightarrow$$​ Species A generally smaller than species B

  •  In parasitism, the parasite (Species A) benefits at the expense of the host (Species B). Generally, parasites are much smaller than their hosts and do not immediately kill them.

• (B) Mutualism $$\rightarrow$$​ Both species A and B positively affected in a positive and obligatory interaction

  • Mutualism is an interaction where both species benefit (+/+), and in many cases, it is obligatory for their survival.

• (C) Commensalism $$\rightarrow$$​ Species A benefits while species B remains unaffected

•  Commensalism is a (+/0) interaction where one species benefits and the other is neither helped nor harmed.

(D) Competition $$\rightarrow$$​  Both species A and B negatively affected in the interaction

• Competition is a (-/-) interaction because both species must contend for the same limited resources, which reduces the fitness of both.