Answer: A. the 99 principle
Step-by-step explanation:
This strategy, often called "charm pricing," involves using pricing that ends in "9" and "99."
With charm pricing, the left digit is reduced from a round number by one cent. We come across this technique every time we make purchases but don’t pay attention. For example, your brain processes $3.00 and $2.99 as different values: To your brain $2.99 is $2.00, which is cheaper than $3.00.
How is this technique effective? It all boils down to how a brand converts numerical values. In 2005, Thomas and Morwitz conducted research they called "the left-digit effect in price cognition." They explained that, “Nine-ending prices will be perceived to be smaller than a price one cent higher if the left-most digit changes to a lower level (e.g., $3.00 to $2.99), but not if the left-most digit remains unchanged (e.g., $3.60 to $3.59).”