To solve this question, the user needs to know the format and properties of a S9(8) COMP data type in mainframe systems.

The S9(8) COMP is a signed 4-byte (32-bit) binary integer data type in IBM mainframe systems. It can store values ranging from -2147483648 to 2147483647. Since S9(8) is a signed data type, the first bit of the binary representation is reserved for the sign of the number (0 for positive and 1 for negative).

To find the maximum value that can be stored in S9(8) COMP, we can use the formula:

Maximum value = (2^(number of bits - 1)) - 1

For S9(8) COMP, the number of bits is 32 (4 bytes x 8 bits per byte), so the formula becomes:

Maximum value = (2^(32 - 1)) - 1

Maximum value = 2,147,483,647

However, since S9(8) COMP is a signed data type, the maximum positive value that can be stored is half of the range, or 2,147,483,647 / 2 = 1,073,741,823.

Now, let's go through each option and explain why it is right or wrong:

A. 999999999: This option is incorrect because the maximum positive value that can be stored in S9(8) COMP is 1,073,741,823, which is less than 999,999,999.

B. 9999999: This option is incorrect because it is less than the maximum positive value that can be stored in S9(8) COMP, which is 1,073,741,823.

C. 99999999: This option is incorrect because it is greater than the maximum positive value that can be stored in S9(8) COMP, which is 1,073,741,823.

D. 99999: This option is incorrect because it is much less than the maximum positive value that can be stored in S9(8) COMP, which is 1,073,741,823.

Therefore, the correct answer is:

The Answer is: C. 99999999