ASCII (American Standard Code for Information Interchange) is a 7-bit character code used to represent letters, numbers, and a wide range of control and punctuation symbols.

Introduction / Context:
ASCII is a foundational character encoding that maps binary values to textual characters. Although modern systems often use Unicode, understanding ASCII’s scope is essential for data interchange, protocols, and legacy systems. ASCII uses 7 bits, allowing 128 code points including control characters and printable symbols.

Given Data / Assumptions:

• ASCII includes uppercase and lowercase letters.
• ASCII includes digits 0–9.
• ASCII includes punctuation and control codes (e.g., CR, LF, ESC).

Concept / Approach:
The 7-bit range (0–127) covers control characters (0–31, 127) and printable characters (32–126): space, digits, uppercase A–Z, lowercase a–z, and punctuation. Therefore, ASCII clearly represents letters, numbers, and other symbols, not just one category. Extended 8-bit “ASCII” variants add locale-specific symbols but the core remains 7-bit.

Step-by-Step Solution:
List ASCII categories: control, digits, letters, punctuation.Confirm inclusion of all three categories in the options.Select the comprehensive choice: all of the above.

Verification / Alternative check:
ASCII tables show, for example, 48–57 for digits, 65–90 for uppercase letters, 97–122 for lowercase letters, and various punctuation codes—verifying coverage.

Why Other Options Are Wrong:
Letters only or numbers only: incomplete and thus incorrect.Other symbols only: incomplete and misses alphanumerics.None of the above: false because ASCII includes all categories.

Common Pitfalls:
Confusing ASCII with Unicode; assuming ASCII is 8-bit; forgetting control characters and whitespace are part of ASCII and crucial to protocols and file formats.

Final Answer:
All of the above