Final answer:
Alphanumeric data in an information system is a combination of letters and numbers which can include special characters, answering the student's query, it is letters and numbers.
Step-by-step explanation:
In an information system, alphanumeric data normally takes the form of letters and numbers, which includes the use of alphabets (such as the twenty-six letters in the English language) and numerals (0-9). All these are symbols that create a language used for communication. Alphanumeric data can include special characters as well, but primarily it is the combination of letters and numbers (option c) that constitutes alphanumeric data. Examples of alphanumeric data include user IDs, product codes, and serial numbers.