Prompt 4

The best explanation for the "Shindo Priest" is that the Americans regarded the Japanese proposal as based on mere superstition. All of the options are valid, this just best explains why the Americans were so against bringing in a Shindo priest. Americans are very supersticious, however, that usually reserved for rabbit's feet, and lucky coins. The Americans most likely thought of the Japanese wishes as superstiction because they did not fully comprehend what the priest does and how important he is to Japanese people.
All of the American's were probably not Christians, because it's not fair to say that everyone in the business world is a Christian. It's too narrow of a reason. Believing it's a superstiction is much more logical than tying it into religion. Also Christians believe that everyting happens for a reason, not in superstition, so therefore they would be more willing to accept a different idea on how to fix something.
Because of what they are asking to do, it's very unlikely that the Japanese would ask to bring in the Shinto Priest if they had shady ways of insuring safety.
This is a good point, but when you work for company, you become a part of that company in Japan. Therefore, the "family" takes care of it's own. This is an unlikely choice because of the way businesses like the one discribed in the interaction. Secondly, because of the "family" situation, its unlikely that the Japanese employeers would be worried about an employee ratting them out.