To answer this question, we need to understand the representation of COMP-3 fields in COBOL.
A COMP-3 field, also known as a packed decimal field, is a type of numeric data storage format in COBOL. It is used to store decimal numbers with a fixed number of digits.
In a COMP-3 field, each digit is represented by a half-byte (4 bits). The sign (positive or negative) is stored in the last half-byte.
The S9(7) notation indicates a signed numeric field with a total of 7 digits.
To calculate the number of bytes occupied by a COMP-3 field, we divide the total number of digits by 2 (since each digit occupies half a byte) and round it up to the nearest whole number.
In this case, the S9(7) field has a total of 7 digits. Dividing 7 by 2 gives us 3.5, which we round up to 4.
Therefore, a S9(7) COMP-3 field occupies 4 bytes.
Let's go through each option to understand why it is correct or incorrect:
Option A) 7 bytes - This option is incorrect because the S9(7) COMP-3 field occupies 4 bytes, not 7.
Option B) 6 bytes - This option is incorrect because the S9(7) COMP-3 field occupies 4 bytes, not 6.
Option C) 5 bytes - This option is incorrect because the S9(7) COMP-3 field occupies 4 bytes, not 5.
Option D) 4 bytes - This option is correct because the S9(7) COMP-3 field occupies 4 bytes.
The correct answer is D.