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.

[EX Q]: Scientists have discovered fossils of the same organisms in many different parts of the world. These fossils provide evidence that
(A) the continents were once joined together (B) most life-forms that existed in the past are still present today (C) most of Earth's surface was once covered by molten rock (D) rocks have been transformed from one type to another
[EX A]: A

[EX Q]: Laura adds 50 mL of boiling water to 100 mL of ice water. If the 150 mL of water is then put into a freezer, at what temperature will the water freeze?
(A) 0C (B) 15C (C) 37C (D) 50C
[EX A]: A

[EX Q]: Cars were once assembled completely by hand. Industrial robots now assemble many car parts. What is a positive effect of using robots?
(A) The assembly takes more time. (B) More workers are needed for assembly. (C) There are fewer injuries to workers. (D) More mistakes are made during the assembly.
[EX A]:
C