Definition: 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.
Input: A scientist was digging for dinosaur bones in a dry river bed. It started to rain and the scientist had to leave the area. If another scientist wanted to continue digging in the same place, he would have to
(A) know how deep the river got when it rained. (B) know how far the river bed is from a town. (C) have accurate notes describing the location. (D) have the weather records for the past few months.
Output:
C