Which data type is used to store a sequence of characters in C?

The data type used to store a sequence of characters in C is Option A: char. In C, you can use an array of characters (often referred to as a "string") or simply a single character variable to store individual characters or sequences of characters.

So, the correct answer is:
Option A: char
In C, you can declare a character array (string) like this:

char myString[] = "Hello, World!";

In this example, 'myString' is an array of characters, and it can store a sequence of characters, including letters, digits, symbols, and spaces.