Based on the graph below, what is the most likely explanation for what happened halfway through year 15?
rabbits
years
14
15
16
a
b
a hot summer
a harsh winter
sharp increase in available land
a sharp decrease in available land
c
a
d

In a study, people were asked to imagine simple occasions that made them happy and to remember events that made them feel proud about themselves. it was observed that the subjects developed an increasingly positive attitude. these changes are known to be healthy, leading to greater physical activity and reducing unhealthy habits. based on this excerpt, we can conclude that a positive attitude .