Final answer:
When prompted to "call authorization center" for a credit transaction, you should immediately call the authorization center for approval.
Step-by-step explanation:
When you receive a prompt on the register to "call authorization center" for a credit transaction, it means that the transaction requires additional approval from the credit card company before it can be processed. In such cases, you should call the authorization center immediately to get the necessary approval.
Option A to continue with the transaction without approval could result in processing an invalid or unauthorized transaction. Option B to suspend the transaction and wait for the customer to return may inconvenience the customer, as they may have to come back to complete the transaction later. Option D to cancel the transaction may not be the best approach, as it could cause dissatisfaction for the customer. Therefore, the best course of action is to choose option C and call the authorization center immediately to ensure the transaction is legitimate.