Final answer:
Option 2, 'Opt-in to e-mail required to avoid SPAM,' is a technology constraint in the e-commerce macro-environment because it relates to the regulatory and technical infrastructure maintaining email communication standards for e-commerce.
Step-by-step explanation:
Among the options presented, number 2) Opt-in to e-mail required to avoid SPAM represents a technology constraint from the e-commerce macro-environment. This is because it directly relates to the technology infrastructure of e-commerce, where regulatory and technical measures such as an opt-in system are necessary to control unsolicited emails or SPAM, ensuring that the communication between businesses and consumers is based on permission marketing principles.
The vast improvement in communications technologies, including the development of the internet, has allowed consumers to purchase goods and services globally, thereby increasing competition and changing the landscape of local and international markets. With the rise of e-commerce, companies must adhere to various technological constraints and regulations that are essential for maintaining privacy, security, and the trust of online consumers.
While options such as the propensity to purchase online, the likelihood of fraudulent transactions, and taxation at the source of purchase may also affect the e-commerce environment, they are not classified as technological constraints but rather as market dynamics and regulatory issues.