Sarah, a student at an american university, has just arrived in bolivia for a study year abroad. when meeting her host parents, she notices that they stand very close to her as they speak. she feels uncomfortable until she realizes that

I believe the answer is: they have different cultural norms concerning the use of space
Bolivian society is very conservative and the way communication occurs between strangers tend to be really restricted.
It is very likely that Bolivian people would felt uncomfortable if exposed to a culture where things such as hugging and kissing is considered as common.