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]: Which of these is a structure that is present in all organisms?
(A) a tissue (B) a cell (C) a stomach (D) a brain
[A]: B

[Q]: Sharpening a pencil and tearing paper are examples of physical changes. Which statement describes why these are physical changes?
(A) There is a change in how the objects are used. (B) There is a change in the appearance of the objects. (C) There is a change in the materials from which the objects are made. (D) There is a change in both the appearance of the objects and the materials from which they are made.
[A]: B

[Q]: All nations need to import and export goods for their economic survival. As a result, many island nations have developed advanced technology for transporting goods by
(A) space. (B) rail. (C) sea. (D) road.
[A]:
C