before scientists determined that deer were the cause of the trillium decrease, what did most people believe was the cause?
a, most people thought that trillium was not getting enough sunlight in the forest. b, most people thought that trillium was not getting enough water in the forest.
c, most people thought that garlic mustard was crowding out trillium in the forest. d, most people thought that garlic mustard was eating the trillium in the forest.

A. Most people thought that trillium was not getting enough sunlight in the forest.

Explanation – Scientists used to believe that the population of trillium decreased because there were not enough sunlight to reach these plants. Later, it was found that deer used to eat the flowers of trillium plant that led to the decrease of its population.

The seed of the trillium plant is very nutritious and hence consumed by the deer. Because of this, trilliums were found to be unlikely to recolonize local areas on their own.