instruction:
You are given a science question (hard-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.
question:
When you make soap bubbles, what is inside the bubbles?
(A) Air (B) Soap (C) Water (D) Nothing
answer:
A

question:
A student is shown a slide of cells from a species of producer in a food web. The student observes that the cells have chloroplasts. What conclusion about the food web is best supported by these findings?
(A) The producers capture energy from sunlight. (B) The food web is found in a terrestrial ecosystem. (C) The producers in the web are single-celled organisms. (D) The food web contains many herbivores and omnivores.
answer:
A

question:
When an electric current is passed through water (H_{2}O) using a specific apparatus, hydrogen (H_{2}) and oxygen (O_{2}) gases form. How can this reaction be shown in a chemical equation?
(A) H_{2}O -> H + O + H (B) 2H_{2}O(l) -> 2H_{2}(g) + O_{2}(g) (C) H:O:H -> H_{2}O (D) H_{2}O(l) -> 2H(g) + O(g)
answer:
B