Answer:
C) human actions altering ecosystems with serious consequences
Step-by-step explanation:
The increase in the manateeĀ“s death during 2011-2012 might be directly related to human actions.
The increase in the number of people during the last 50 years to more than 500,000 individuals, and probably the lack of policies and regulation, lead to an enhance in water pollution by sewage tank leaks.
Pollution probably caused a gradual decrease in the manateeĀ“s principal source of food, which also caused an increase in the toxic algae population.
Algae caused the death of manatees as a consequence of human action that altered the natural ecosystem by polluting water.