To answer this question, you need to understand the different data types and their ranges.
Option A) System.UInt16 - This option is correct because UInt16 is an unsigned 16-bit integer data type in C#, which means it can only store positive numbers. It has a range of 0 to 65,535, which satisfies the given criteria.
Option B) int - This option is incorrect because an int is a signed 32-bit integer data type in C#, which means it can store both positive and negative numbers. It has a larger range from -2,147,483,648 to 2,147,483,647, which exceeds the given criteria.
Option C) System.String - This option is incorrect because a string is not a numeric data type. It is used to store text and not numbers.
Option D) System.IntPtr - This option is incorrect because IntPtr is a platform-specific pointer data type and not a numeric data type. It is used to store memory addresses.
The correct answer is Option A) System.UInt16. This option is correct because it is an unsigned 16-bit integer data type in C# that meets the given criteria of always being a number and not being greater than 65,535.