Throughout the Northern Hemisphere, Plant Species Are Blooming Several Weeks

Throughout the Northern Hemisphere, plant species are blooming several weeks earlier than they did 50 years ago.Also, their insect pollinators are emerging and reproducing earlier, so they require earlier-blooming flowers to provide pollen and nectar.These changes in timing are most likely caused by

A) rising temperatures due to climate change.
B) rapid genetic changes in the organisms' behavior.
C) loss of habitat, requiring more rapid life cycles.
D) increasing biodiversity, requiring more compressed life cycles.
E) lower temperatures due to climate change.