what strategy should he use to improve his communication with employees from other cultures?
a. avoid eye contact when communicating with others.
b. interact more with people from different backgrounds.
c. limit communication to written communication.
d. limit interactions to work-related issues only

I think that the best option is: 

B.Interact more with people from different backgrounds.

In general, if we interact more with people of different cultures, we can learn to communicate better. This is actually true for everything: if we do something a lot, we become better at it and we learn it.

What is not good is limiting communication: this will only potentially offend other people.