Who most likely is the speaker

参考答案:B
答案解析:[听力原文]
Ladies and gentleman, this is Emily Cox, your chief flight attendant. On behalf of the pilot and the entire crew, I’d like to welcome you aboard flight 735 nonstop service from London to Paris. We’ll be departing London shortly and we’ll arrive in Paris at approximately 9:30 p.m. local time. As we prepare for take off, please review the safety card in the seat pocket in front of you and direct your attention to the flight attendants doing safety demonstrations. Once we reach a comfortable altitude, we will serve some refreshments. For your entertainment on today’s flight, we will be showing the movie "Holiday in Bali." We will pass out headphones along with the refreshments. Please remember to stay in your seat after take off until the pilot turns off the seat belt light. We thank you for flying with us, and we hope you enjoy the flight.

[解析] 这是在飞机内的广播通知，开头部分提到Ladies and gentleman, this is Emily Cox, your chief flight attendant.由此可知说话人是本航班的乘务长。