Function Proper(text) in MS Word means:

The function Proper(text), while more commonly known in Microsoft Excel, refers to a text case conversion that capitalizes the first letter of each word in a given text string and converts the remaining letters to lowercase. In MS Word, this functionality is achieved through the 'Change Case' option, specifically 'Capitalize Each Word' (often referred to as Proper Case) or 'Sentence case' which capitalizes the first letter of a sentence.

• Capitalize the first letter in a text string is the most accurate description, implying the first letter of each word or the sentence.
• 'Capitalize the last letter in a text string' is not a standard text case function.
• 'Capitalize all letters in a text string' describes the 'UPPER()' function or 'ALL CAPS' formatting.
• Therefore, 'None of these' is incorrect as option A correctly describes the primary effect of 'Proper' case.

This function is vital for consistent and professional text formatting.