Read and choose the correct option that answers the question. Did you know that there is a coral reef in the Amazon River? This coral reef measures a thousand kilometers and is in the northeast of Brazil. The danger of extinction of the Amazon reef is easy when it is warmer in the waters of the river. The Amazon River begins in the Andes, Peru, then passes through Venezuela and Brazil and out into the Atlantic Ocean. The Amazon River is the habitat of many animals, such as small fish that eat meat or pink dolphins that are in danger of extinction.

Based on the passage, what may be a concern in this particular habitat?
A. Drought
B. Global warming
C. Ice melting
D. Rainfall