Question

What is the purpose of the transitional phrase in the following sentence: The Amazon Rainforest boasts more species than almost any other location in the world. Now however, climate change is taking a toll on the amount of rainfall in the forest which will negatively affect the ability of species to survive.

“Now however” is used to indicate location.

“Now however” is used to indicate classification.

“Now however” is used to indicate the passing of time.

“Now however” is used to indicate summation.