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.

[Q]: The basic life functions of an organism are carried on by  
 (A) cells (B) nutrients (C) atoms (D) hormones
[A]: A


[Q]: A large number of species on Earth became extinct during a short time period about 65 million years ago. Based on this pattern of extinction, which is the most likely cause?  
 (A) gradual climate change (B) continued climate stability (C) sudden global climate change (D) gradual ecosystem succession
[A]: C


[Q]: Which process in the water cycle is directly caused by the heat from the Sun?  
 (A) evaporation (B) runoff (C) cloud formation (D) stream flow
[A]:
A