Which of the following statements is true of radio frequency identification (RFID) tags? A. They represent numerical data of a product by varying the thickness and pattern of vertical bars printed on the product’s packaging. B. They require direct line-of-sight scanning for the radio waves to scan a product perfectly. C. They require a reader that tunes into a specific frequency to determine the number and location of products. D. They are installed in a handheld or pen-type scanner that reads and records data instantly.