In C language, integers can be expressed in three forms: octal, decimal and hexadecimal. Decimal numbers take the value of 0-9 without prefix. Octal numbers take values from 0 to 7, and must be prefixed with 0; Hexadecimal values are: 0 ~ 9, a ~ f or a ~ f, and the prefix is 0X or o) In addition, for long integers, the suffix L or L is used, and unsigned numbers are represented by the suffix U or U; 0L means decimal long integer 0, so option A is correct; 0Xa stands for hexadecimal number A, that is, decimal value l0, so option C is correct; 200U means decimal unsigned integer 200, so option d is correct; Negative numbers are usually stored in memory in the form of two's complement. When displayed in octal format, the prefix 0 comes first, and the following values are converted from two's complement to octal format without negative sign. In C program, only decimal numbers can be negative. Octal and hexadecimal numbers can only be integers. So the answer is 8.