It cannot be the production approach as it directly says that there is an advertising campaign. Businesses which use the production approach have the mindset that the the demand of their product is higher than the supply for it, meaning that no advertising campaign is needed. The last point you said does not have any particular relevance to the approaches (except for marketing, of course), and deals with a different topic.It's definitely not selling approach. Selling approach is about tryingto sell existing products/ products that are not innovative. Marketing approach is abotu market research, it is the same as production approach but finding out what customers want - the business did not do market research. It is therefore production approach. Despite advertising, the main feature of the business was its product. Enough arguing now.
But the marketing approach is solely based around collecting information that determines the needs and wants of the customer. The question does not specifically state that any research has been conducted. It's like saying that throughout the 1920s-1960s, when the selling approach dominated, that developing new or innovative products is impossible without market research.No, it is the marketing approach. It's definitely not the selling approach, because the all important indicator of that is the use of a salesperson to physically bring the product to the consumer, which the business did not do. The marketing approach involves creating a product that a large group of consumers will desire and that caters to their needs AND THEN promoting it appropriately through the use of advertising. This is EXACTLY what the business in the question has done. Sorry guys
Also, you have only outlined one aspect of the selling approach, it has a much wider scope than just the "use of a salesperson".