You are given a science question (hard-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. 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.

The students in a class are making a scale model. They need a material that they can easily bend into a circle. Which of the following objects is best for the students to use?  
 (A) copper wire (B) glass rod (C) lead pipe (D) wooden stick
A

After a heavy rain, a mudslide flows into a pond and mud mixes into the water. Which of the following is most likely to happen?  
 (A) Fish will have more food. (B) Trees will be able to get more light. (C) Raccoons will not be able to find food. (D) Underwater plants will receive less light.
D

Currently, Antarctica is the coldest and driest place on Earth. Paleontologists have found dinosaur fossils in rock layers below the ice. Based on this evidence, which is a reasonable conclusion about the climate of Antarctica in the past?  
 (A) Antarctica has always had the same climate as at present. (B) At some time in the past, Antarctica was a hot, dry desert. (C) At some time in the past, Antarctica was much warmer and wetter. (D) At some time in the past, Antarctica was colder and wetter than it is now.

C