An increase in phosphate levels in a lake increases the population of algae in the lake. Increased algae blocks sunlight into the lake and results in a decrease in dissolved oxygen in the lake's water. Which of the following should be expected as a result?

Available choices:
a). Plant populations in the lake increase..
b). More predatory birds feed on lake animals..
c). Phosphate levels in the lake decrease..
d). Fish populations in the lake decline..
d).