Final answer:
E-commerce refers specifically to online transactions, not to all computer networks, so the correct answer is 'all types of transactions'.
Step-by-step explanation:
E-commerce includes “all types of transactions” involving the buying and selling of goods and services over the internet. It does not encompass all types of computer networks, as not all computer networks are designed for conducting commercial transactions. Therefore, the correct answer to the question is b. all types of transactions. E-commerce can occur on various platforms including websites, social media, and other online marketplaces, enabling businesses and consumers to transact digitally.