To solve this problem, we need to identify where the receptors for sperm binding are located in mammals. Let's analyze each option:$\newline \bullet$Corona radiata:$\newline$ - The corona radiata is the outermost layer of cells surrounding the oocyte. It is composed of granulosa cells.$\newline$ - It does not contain specific receptors for sperm binding.$\newline \bullet$Vitelline membrane:$\newline$ - The vitelline membrane is a layer surrounding the plasma membrane of the oocyte.$\newline$ - In mammals, this term is not commonly used, and it is not the site for sperm binding.$\newline \bullet$Perivitelline space:$\newline$ - The perivitelline space is the area between the zona pellucida and the oocyte membrane.$\newline$ - It does not contain receptors for sperm binding.$\newline \bullet$Zona pellucida:$\newline$ - The zona pellucida is a glycoprotein layer surrounding the plasma membrane of the oocyte.$\newline$ - It contains specific receptors for sperm binding, which are crucial for the fertilization process.$\newline$Therefore, the correct answer is Option 4: Zona pellucida.