Detailed Instructions: 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.
Problem:Two students are studying what makes ice melt fastest. They want to conduct an investigation. During which of these steps in their investigation will they measure the ice?  
 (A) showing some graphs (B) making a conclusion (C) developing a hypothesis (D) collecting some data
Solution:
D