To solve this problem, we need to match the interactions in List I with their corresponding ecological relationships in List II. Let's analyze each interaction:$\newline \bullet$A. A Leopard and a Lion in a forest/grassland:$\newline$ - Both the leopard and the lion are predators that may compete for the same prey in a shared habitat.$\newline$ - This interaction is an example of competition.$\newline$ - This matches with I. Competition.$\newline \bullet$B. A Cuckoo laying egg in a Crow's nest:$\newline$ - The cuckoo lays its eggs in the nests of other bird species, such as crows, to have them raise its young.$\newline$ - This is an example of brood parasitism.$\newline$ - This matches with II. Brood parasitism.$\newline \bullet$C. Fungi and root of a higher plant in Mycorrhizae:$\newline$ - Mycorrhizae are symbiotic associations between fungi and plant roots, where both partners benefit.$\newline$ - This is an example of mutualism.$\newline$ - This matches with III. Mutualism.$\newline \bullet$D. A cattle egret and a Cattle in a field:$\newline$ - Cattle egrets feed on insects stirred up by cattle as they graze, benefiting from the cattle's movement without affecting them.$\newline$ - This is an example of commensalism.$\newline$ - This matches with IV. Commensalism.$\newline$Now, let's match the items from List I with List II:$\newline A \rightarrow I, B \rightarrow II, C \rightarrow III, D \rightarrow IV \newline$This corresponds to Option 1.