Observe the given chart and identify what it represents.

$A$: Estuary constitutes one of the most productive ecosystems.
$R$: It represents a transition zone between two populations of a species.

Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

In a grassland ecosystem, match the trophic levels with their correct example species:

$(a)$ Fourth trophic level	$(i)$ Crow
$(b)$ Second trophic level	$(ii)$ Vulture
$(c)$ First trophic level	$(iii)$ Rabbit
$(d)$ Third trophic level	$(iv)$ Grass

Select the correct option:

Match the trophic levels with their correct species examples in a grassland ecosystem.

$(a)$ Fourth trophic level	$(i)$ Crow
$(b)$ Second trophic level	$(ii)$ Vulture
$(c)$ First trophic level	$(iii)$ Rabbit
$(d)$ Third trophic level	$(iv)$ Grass

Select the correct option:

Which of the following exhibits scavenging?