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.

[EX Q]: Scientists discovered that although infectious bacteria may develop immunity to antibiotic medications, some bacteria are unable to resist certain peptides, which act as natural antibiotic substances inside the human body. This discovery led to the development of which new technology?  
 (A) artificial substances that mimic human peptides (B) antibiotics that can be absorbed through the skin (C) bacteria that attack antibiotic-resistant organisms (D) antibiotics that adapt in response to bacterial immunity
[EX A]: A

[EX Q]: The radiant energy that comes to Earth from the Sun is  
 (A) only one wavelength that we see as yellow. (B) a narrow band of wavelengths that is entirely visible light. (C) mostly long wavelengths that become heat energy. (D) a range of many wavelengths from long to very short.
[EX A]: D

[EX Q]: A student conducted an experiment to see how much sugar could dissolve in water. The student wrote down how many teaspoons of sugar were added to the water. What is the most likely reason the student recorded the information?  
 (A) to see which kind of water to use (B) to know which kind of sugar to use (C) to build a model of the experiment (D) to be able to repeat the experiment
[EX A]:
D