Currently, most of the mass of the matter of the universe is believed to consist of
A) baryonic matter, made up of protons and neutrons.
B) tachyonic matter, travelling only faster than the speed of light.
C) dark matter not made of protons and neutrons.
D) dark energy.
E) tiny but very numerous black holes.
Question 2
What evidence from the careful examination of impact craters provides evidence that Mars had surface water long ago?
A) indistinct rims of many large craters due to water erosion
B) lack of small craters which would have been erased by ancient rainfall
C) channels where water once flowed between crater lakes
D) all of these
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