When asked about those people who say his Sriracha sauce is too spicy, David Tran jokingly suggests they "use less" of the product. Sriracha's use of a single marketing mix for all potential customers means that the company is using:

The correct answer is letter "D": an undifferentiated approach.

Explanation:

While talking about the market mix, the undifferentiated approach refers to providing customers the same product without considering specific expectations of one sector of the market or another. Companies implementing this method do not require to segment their market since they hope their product will reach as many consumers as possible as it is.  

Firms with this strategy have typically remained in the market for long periods and prefer to keep the image of a company with a traditional product than one that modifies over time.