Which of the Following Price-Related Actions by a Manufacturer Most

Which of the following price-related actions by a manufacturer most likely would be a violation of the Robinson-Patman Act?

A) Offering a lower price to only one buyer to match a competitor's price.
B) Selling to all its customers at uniform prices.
C) Granting a lower price to a buyer because of a large-quantity purchase.
D) Giving a special advertising allowance to a retailer that was having difficulty competing in its local market.
E) None of the above is a violation.