You are given a science question (easy-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.

A student conducts an investigation. In order to make a valid conclusion, she must  
 (A) have a testable hypothesis. (B) place the data in a graph. (C) use the best technology. (D) test multiple variables.
A

Which describes a specific characteristic necessary for survival in the desert?  
 (A) conserving water (B) hiding from predators (C) hibernating for long periods (D) producing many offspring
A

A student mixes salt and water in a beaker to form a solution. What properties of the substances would allow the student to then separate the components?  
 (A) densities (B) particle sizes (C) boiling points (D) electrical conductivity

C