Final answer:
To make an external call, you typically dial 9 to obtain an outside line and then omit any initial 0 that is usually required for calling locally within certain regions. The correct option is A.
Step-by-step explanation:
To place a call outside of the building, you typically need to dial the number for an outside line first. This is often the number 9. After dialing 9, you can then dial the remaining numbers to complete the phone number. It is important to note that if there are extra zero digits at the beginning or end of the number, you would not include them. For example, if the phone number is 0123456789, you would dial 9123456789 to make the call.
To place a call outside of the building, the initial number you have to dial is typically 9; this is a common access code used in many multi-line telephone systems such as those in offices or hotels to get an outside line. When you dial 9 first, you are connecting to an external line which allows you to make a call that exits the local phone system.
However, the numbers you do not include in the phone number that follows could depend on the phone system's programming. In some cases, if you are dialing a local number, you might not need to include the initial 0 that is sometimes used in certain regions or countries as a trunk prefix. Nonetheless, based on the given options and typical practices, the correct answer is likely 'A) 9; 0.'