What part of marketing mix deals with key to picking up customer for buisness growth

all elements of the mix marketing are necessary (5p): product, price, place, publicity and personal contact their order as follows presents that product and price are the most important to achieve sales and business growth because the quality of product is a concern of our client for satisfaction of their needs and as we saw that the expectations of our customers have become quality and developed which commit us to improve the quality of our product to be align to their requirements.then there is the price effect on marketing that is directly connected with the place of marketing (depends on category of customers).
and also depends on the way to promote products and the staff of the spots that need to be qualified.