What output does the expression String.Format("Input = {0} and Output = {1}","1","2") produce?

The expression String.Format("Input = {0} and Output = {1}", "1", "2") produces the output "Input = 1 and Output = 2". This is because String.Format is designed to insert values into a string template at designated placeholders, which in this case are represented by {0} and {1}.

Here, {0} is replaced with the first argument "1" and {1} is replaced with the second argument "2". The rest of the string remains unchanged, resulting in the exact output matching the structure of the original string provided in the Format method.

This format is particularly useful for generating formatted strings dynamically while maintaining clarity and ease of understanding within the code. The other options do not accurately reflect the output of the String.Format method as they either omit necessary elements or misrepresent the formatting specified in the string template.