The correct answer to this open question is the following.
Although there are no options attached we can say the following.
Researchers best overcome the language barrier issues that arise when they administer questionnaires to people in foreign countries by doing the following.
These researchers can hire native individuals that live in the target nation so they can help write the questions of the surveys in the correct form of language so it could be understood by local people.
This is very important because researchers need precise answers to support their surveys. So local people must correctly understand the questions because the answers are what is going to be interpreted by researchers.