Answer: a. Product or service with better features or functions.
d. Rareness factor, meaning that competitors cannot offer the same set of values to this customer
Step-by-step explanation:
Sustainable Competitive Advantage refers to the quality that a company has of being able to stay ahead of it's competitors in the long term.
The main way to do this is Value creation. The company has to give to the consumer, something that the consumer will value and keep coming back for.
One of those ways is to give consumers a better product with better features and functions. This will enable consumers to associate high quality products with a company leading to them having a better market share.
Another way is the RARENESS FACTOR. Offering a product or something in that product that consumers consider rare will create value for the company because rare things are often sought after.
If a Company's products are considered rare, consumers will value them more.