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.

Sickle cell anemia is a genetic disease caused by an autosomal recessive gene. If each parent carries one sickle cell allele, what are the chances that their child will have sickle cell anemia?
(A) no chance (B) one in four (C) two in four (D) three in four
B

Air is composed of many different substances. Which of the following components of air is a compound rather than an element?
(A) Argon, Ar (B) Oxygen, O2 (C) Water, H2O (D) Nitrogen, N2
C

The force of gravitational attraction between Earth and any object on Earth is measured as
(A) mass. (B) weight. (C) volume. (D) density.
B