To solve this problem, we need to match the items in Column I with the appropriate descriptions in Column II. Let's analyze each item:$\newline \bullet$a. Organ of Corti:$\newline$ - The Organ of Corti is located on the basilar membrane within the cochlea of the inner ear.$\newline$ - This matches with iv.$\newline \bullet$b. Cochlea:$\newline$ - The cochlea is a coiled part of the labyrinth in the inner ear.$\newline$ - This matches with ii.$\newline \bullet$c. Eustachian tube:$\newline$ - The Eustachian tube connects the middle ear to the pharynx and helps equalize pressure.$\newline$ - This matches with i.$\newline \bullet$d. Stapes:$\newline$ - The stapes is a bone in the middle ear that is attached to the oval window.$\newline$ - This matches with iii.$\newline$Now, let's match the items from Column I with Column II:$\newline a \rightarrow iv, b \rightarrow ii, c \rightarrow i, d \rightarrow iii \newline$This corresponds to Option 2.