The terminal device that functions as a cash register, computer terminal, and OCR reader is the:

Answer: Option D

A point of sale terminal (POS terminal) is an electronic device used to process card payments at retail locations. A POS terminal generally does the following:
1. Reads the information off a customer’s credit or debit card
2. Checks whether the funds in a customer’s bank account are sufficient
3. Transfers the funds from the customer’s account to the seller’s account (or at least, accounts for the transfer with the credit card network)
4. Records the transaction and prints a receipt

Source : techopedia.com