Right, "x" is a string literal, which the compiler sees as an array of characters, or 'x' and 0 or '/0'.
So you're comparing a single character constant to a temporary multi-character array. Single quotes indicate single character constants.
NP, it's also worth noting that the compiler converts both character literals like 'x' and '\0' and string literals like "hello" to their ascii numerical equivalents. So the compiler warning you of a comparison between an integer and pointer shows you how the compiler sees the expression c[1] == "x", it converts the string character element c[1] to an integer, and the string literal "x" to a pointer to two integer values (an array), 120 and 0.