What is one of the main reasons volcanic eruptions can be predicted in enough time?

One main reason of volcanic eruptions being predicted is the fact that temperatures around the volcano tend to rise as the activity increases. This means that we can use satellite cameras and thermal imaging techniques to detect the heat around a volcano.

Also, another reason would be that hundreds of small earthquakes are caused as magma rises up through the cracks in the Earth's crust. We can use seismometers to detect the earthquakes and in turn detect volcanic eruptions as well. 

Answer barren with few trees, in the northern hemisphere;

Conflicts arising from drug cartels and goverment corruption is an issue that would most likely be considered as mexico's most challenging problem of today. the correct option among all the options that are given in the question is the third option or option "c". this problem has continued for a very long time.