To solve this problem, we need to match the geological eras in List I with the corresponding dominant life forms in List II. Let's analyze each era:$\newline \bullet$A. Mesozoic Era:$\newline$ - The Mesozoic Era is known as the age of reptiles and is characterized by the dominance of dinosaurs, along with the emergence of birds.$\newline$ - This matches with III. Birds & Reptiles.$\newline \bullet$B. Proterozoic Era:$\newline$ - The Proterozoic Era is marked by the presence of lower invertebrates and the first multicellular life forms.$\newline$