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

In the carbon cycle,the source of carbon for plants is:

Identify the possible link $A$ in the following food chain.
Plant $\rightarrow$ Insect $\rightarrow$ Frog $\rightarrow$ $A$ $\rightarrow$ Eagle

Match the following columns:

Column-$I$	Column-$II$
$(a)$ Earthworm	$(i)$ Pioneer species
$(b)$ Succession	$(ii)$ Detritivores
$(c)$ Ecosystem service	$(iii)$ Birth rate
$(d)$ Population growth	$(iv)$ Pollination

$Mr. X$ is eating curd. What is his trophic level in the food chain for this food?

In a pond ecosystem,which organisms can occupy more than one trophic level?