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.

Diamonds are sometimes used as the tips of drill bits. Which physical property of a diamond MOST likely makes it a good cutting tool?  
 (A) its electrical properties (B) its thermal properties (C) its hardness (D) its density
C

Which characteristic of frogs is an adaptation to living in water?  
 (A) strong legs (B) webbed feet (C) dull colors (D) moist skin
B

Which best describes transportation technology?  
 (A) a system that is used to move people and products (B) an enterprise that changes raw materials into goods (C) the building and finishing of structures (D) the conversion of mechanical energy into heat energy

A