The interaction between sea anemone and clown fish is :

The correct answer is Option (1) → Commensalism

Option (1) Commensalism — Correct. The clown fish gets protection; the sea anemone gains nothing and loses nothing.

NCERT Extract:
Population Interactions – “… Another example of commensalism is the interaction between sea anemone that has stinging tentacles and the clown fish that lives among them. The fish gets protection from predators which stay away from the stinging tentacles. The anemone does not appear to derive any benefit by hosting the clown fish.”