In this task, you need to answer basic science questions. For each question, several terms are intentionally masked with ***. This masking can cover very few or many of the question words. Clearly, if masked terms are important, the modified question will be impossible to answer. Please indicate the correct answer with one of the following responses: "A", "B", "C", "D" or "E". While "A"-"D" correspond to the answer options provided in the input, "E" represents "I don't know" for questions that do not provide enough information. Respond via "E" if the question is not answerable. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'.

[Q]: Question: Which example best shows *** that make up the *** *** in the *** ***?  (A) heart, blood, vessels (B) nose, trachea, lungs (C) brain, spinal cord, nerves (D) esophagus, stomach, intestine.
[A]: E.


[Q]: Question: *** *** *** when they *** their own ***. Which *** of *** is *** by *** for making ***?  (A) electrical (B) heat (C) light (D) mechanica.
[A]: E.


[Q]: Question: Which of the following represents a *** ***?  (A) a sugar cube dissolving in water. (B) ice cubes forming in a freezer. (C) ice cream melting in a bowl. (D) a cake baking in an oven.
[A]:
E.