Deforestation is a major issue primarily in which country? malaysia laos cambodia indonesia

It's not easy to answer the question, as all of the places suffer from deforestation. 

For example, Borneo, an island shared by Indonesia and Malaysia ( and Brunei) is suffering a great deforestation on both the Indonesian and the Malaysian side. 

However, from all the choices I would go for Malaysia, as it is undergoing deforestation at the fastest rate among the mentioned countries. 

It used to once be completely covered by a forest, but in the last 50 years, almost half of that forest dissappeared (typically to make place for palm farms)

The study of where things are