Political issues that may lead to the creation of political boundaries include
a.
shifts of riverbeds
b.
extreme climate changes
c.
conflicts between two neighboring groups
d.
trade agreements between existing countries

C. Conflicts between two neighboring groups.  You have to think politics since the question wants to know what political issues may lead to the creation of political boundaries.  Shifts of riverbeds and extreme climate changes are changes in physical boundaries.  Political boundaries are formed for political reasons like disputes between countries or a peaceful agreement between neighboring groups.  Trade agreements that already exist between two countries may change due to a conflict but since one of the answers is already a conflict between two neighboring groups, that is your best answer.

answer; (disease);