Answer:
The correct answer is the last option.
Step-by-step explanation:
Before calling a potential costumer, all the options are helpful for the telemarketer:
The costumer's age will help the telemarketer choose the proper vocabulary to address to the potential costumer.
The address might help with the costumer's credit rating too, since the address is very important when it comes to purchase power and credit rating.
Due to this, the correct option is letter D.