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The answer is A. The ratio of the triangles is 2:1 This is because BC is twice as long as YZ. The triangles are similar so they keep the proportion for all the sides. AC is 11 because XZ is 5.5 so it is double. XY is 3.5 as it is half as long as AB which is 7. This makes the proportion of all the sides 2 to 1. Please let me know if you need any clarification. I'm always happy to answer your questions.