After Reading the Paragraph Below, Answer the Question(s) That Follow(s)

After reading the paragraph below, answer the question(s) that follow(s) .
Honeybee populations in North America have been in dramatic decline over the past decade or so. The exact cause(s) are not well understood, but pesticides and mites have both been blamed. There is an urgency to solve this problem though, since honeybees play such an important role in their ecosystems. In addition to beekeepers and honey producers, many farmers are also concerned about what is going on.
-Why are bees of such importance to ecosystem health (choose the most complete answer) ?

A) because honeybees have a symbiotic relationship with flowering plants
B) because honeybees have a mutualistic symbiosis with flowering plants
C) because honeybees have a diffuse mutualistic with flowering plants that involves many plant species
D) because honeybees have a diffuse parasitic relationship with flowering plants