Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

A trader observes that the 50-day moving average for the S&P 500 Index recently crossed below its long-term 200-day moving average. This situation is referred to as a:
Option A:death cross.
Option B:golden cross.
Option C:Bollinger Band.

Answer: A