Q: In this task, you're given an article, a question which often contains a blank and four options (associated with "A", "B", "C", "D"). Your task is to find the correct answer (from the given options) for the question from the given article and return one of the options from "A", "B", "C", and "D". Do not generate anything else apart from one of the following characters: "A", "B", "C", "D". There is only one correct answer for each question.
Article: Raising a baby takes a lot of work, especially when that baby is a king penguin. Now, it looks like climate change will make life even harder for these birds. A new study suggests that warmer waters could make their numbers _ Most king penguins live on the Crozet Archipelago, a group of islands in the Indian Ocean, about 1,000 miles north of Antarctica. After the penguin chicks are born in November (which is summer in the Southern Hemisphere), both parents spend 4 months collecting fish to feed their children. When the fish move to deeper waters in March, the adults leave their chicks alone for months. They swim hundreds of miles south. There, near the Antarctic ice, they spend the winter eating seafood, such as squid, to add their own energy stores. In October, nearly a year after their chicks are born, the parents return to feed and finish raising them. Scientists from the French National Center for Scientific Research (CNRS) in prefix = st1 /Strasbourg,France, have been studying king penguins on the Crozet Archipelago for a decade. Starting in 1998, Yvon Le Maho and other researchers implanted electronic ID tags under the skin of hundreds of penguins. The tags have allowed Le Maho's team to know the details about them, such as how long they live, whether they return from their winter trips, and if their chicks manage to survive the winter. Ocean surface temperatures vary from year to year. And former research had shown that fewer squid, fish and other creatures grow when the water is warmer. Le Maho suspected that this drop in the food supply would make it harder for adult penguins to survive the tough times ahead. King penguins can live for up to 30 years. And for now, the population still appears healthy. But a warming trend could cause big trouble for a bird that depends on cold and ice.
Question: What's the main idea of this passage?
Options: (A) Ocean warming may threaten king penguins (B) The Crozet Archipelago is the world of king penguins (C) Scientists support the protection of king penguins (D) King penguins' habitat is in great danger
A:
A