scientists studying squirrels in a forest observed that the squirrel population decrease over a period of five years. which statement is the most likely explanation for the decrease in the population?

1.An increment of predators

2.unavailability of food resources due to change in climate causing famine

3.Spread of diseases over time that might kill the squirrels

4.An increment of squirrels which caused high competition on food,thus some of them had to migrate

5.Might be fire break out over some time that caused death to some squirrels in the reasoning of the period of time

c. orbital shape i hope this is correct