How many characters are there in ASCII?

The correct number of characters in ASCII is 128. ASCII, which stands for American Standard Code for Information Interchange, is a character encoding standard that uses 7 bits to represent each character, allowing for a total of 128 unique characters. These characters include control characters (like carriage return and tab), digits (0 through 9), uppercase letters (A through Z), lowercase letters (a through z), and various punctuation marks and symbols.

The reason the other options are incorrect revolves around their respective character limits. The option indicating 256 refers to an extended version of ASCII called Extended ASCII, which utilizes 8 bits and accommodates 256 characters, but this goes beyond the original standard ASCII character set. The options of 512 and 64 are inaccurate in the context of ASCII as they exceed the defined limits of both standard and extended ASCII. Therefore, the universally accepted total for standard ASCII remains at 128.