To solve this problem, we need to match the individuals in List I with their corresponding contributions in List II. Let's analyze each individual:$\newline \bullet$A. Robert May:$\newline$Robert May is known for his work on global species diversity, estimating it to be about 7 million.$\newline$This matches with III.$\newline \bullet$B. Alexander von Humboldt:$\newline$Alexander von Humboldt is famous for his studies on the species-area relationship, which describes how the number of species increases with the area surveyed.$\newline$This matches with I.$\newline \bullet$C. Paul Ehrlich:$\newline$Paul Ehrlich proposed the rivet popper hypothesis, which compares the ecosystem to an airplane wing where each species is like a rivet.$\newline$This matches with IV.$\newline \bullet$D. David Tilman:$\newline$David Tilman is known for conducting long-term ecosystem experiments using outdoor plots to study biodiversity and ecosystem functioning.$\newline$This matches with II.$\newline$Now, let's match the items from List I with List II:$\newline A \rightarrow III, B \rightarrow I, C \rightarrow IV, D \rightarrow II \newline$This corresponds to Option 4.