聚焦径向偏振飞秒脉冲激光烧蚀熔融石英表面，在多脉冲烧蚀下，形成的裂纹图样是[     ] 
A、同心环形裂纹；
B、径向分布的裂纹；
C、单环形裂纹；
D、一个烧蚀坑；

单项选择题Look at the title, subtitle, source, picture and notes of the news article introduced in task 1. Predict again what the article might be about. Scientists aim to keep whales from the being biggest losers in sailboat races New guidelines could help prevent often-deadly collisions with boats Washington Post, July 10, 2017 Two humpback whales crest next to a sailboat off the coast of Cape Cod, Massachusetts, in 2010. Collisions between racing sailboats and whales are often deadly for the animals, so scientists and racing groups are working together to reduce the chance of collisions. (Heidi Hansen Whale and Dolphin Conservation via AP) Question: The news article might be about ____.

单项选择题To maintain the unity of the writing, you should leave out the sentences that are _______ the thesis. A、apt to B、irrelevant to C、relevant to D、inclined to