Final answer:
The main idea of the provided text, which discusses cultural norms in greetings, is found in sentence option a. 1. It contrasts the expectations of a firm handshake and direct eye contact in America's western regions with other cultures where this might be considered rude.
Step-by-step explanation:
The stated main idea in the question 'In America -- especially out West -- a firm handshake and a direct look in the eye are expected when men meet one another; in many cultures, this would be considered very rude.' is identified in sentence number a. 1.
This discussion highlights the cultural norms and behaviors, such as greetings and the appropriate use of personal space, that vary across different societies. For instance, a firm handshake and direct eye contact are common in the United States, particularly in Western regions, whereas in other cultures such actions may be seen as disrespectful or aggressive.
Furthermore, variations in cultural values and the interpretation of physical closeness in public display how different societies define and perceive personal space and nonverbal communication.