Answer:
Businesses that rely on a physical infrastructure.
Explanation:
e-commerce is a short for electronic commerce and it can be defined as a marketing strategy that deals with meeting the needs of consumers, by selling products or services to the consumers over the internet.
This ultimately implies that, e-commerce is strictly based on the buying and selling of goods or services electronically, over the internet or through a digital platform. Also, the payment for such goods or services are typically done over the internet such as online payment services.
In view of the above details, businesses that rely on a physical infrastructure poses the highest degree of difficulty in e-commerce because it's only dependent online retailing.