In the context of the Differentiation (Quality) vs Efficiency trade-off curve, the efficient frontier is defined by:

The companies that have the greatest profits

The companies that provide maximum quality for a given cost

The companies that achieve minimum cost

The companies that provide maximum quality

Apple is able to retain most of the profits from their industry and value chain because:

Apple has the best marketing in the industry

Their products are relatively inexpensive to make compared to their competitor products

Apple designs their products and supply chains to their own advantage

Apple does not invest as much in technology and research as their peers