Over the course of 150 years, an area filled with weeds becomes more diverse and weeds are replaced by grasses, shrubs, and ultimately oaks.  This process is defined as
                            
                         
                        
                            
                        
                             
                            
                            
                            
                                Explanation
                            
                                
                                    Answer: C, Succession.  Succession is the ordered shift in composition and structure of an ecological community.
Key Takeaway: Of the choices, only succession can define a change in an environment.  Mutation, adaptation, divergence, and convergence all describe changes in an individual or group of organisms.