Which Statement About Tilman and Colleagues' Studies of the Diatoms

Which statement about Tilman and colleagues' studies of the diatoms Synedra and Asterionella is true?

A) The species that reached the highest stable population when grown alone drove the other species to extinction.
B) The species that reduced silica levels the furthest when grown alone drove the other species to extinction.
C) Both species were able to coexist when grown together.
D) The species that went extinct varied at random in different trials; sometimes it was Synedra, sometimes it was Asterionella.