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.

Which property of air does a barometer measure?  
 (A) speed (B) pressure (C) humidity (D) temperature
B

The first telescopes were invented hundreds of years ago. Which was discovered as a result of this invention?  
 (A) the moons of Jupiter (B) the bacteria that causes disease (C) the deep-sea trenches in the ocean (D) the parts of a plant that perform photosynthesis
A

When a neutral atom gains or loses electrons, it becomes  
 (A) more stable. (B) an isotope. (C) an ion. (D) less charged.

C