Mutliple choice question there is no overall change in reactents and products whenever a chemical reaction

A. goes in one direction
B. goes in two directions
C. reaches equilibruim
D. proceeds slowly

Which best describes the present-day universe? opaque, expanding very slowly, stars produce heavy elements transparent, expanding at an accelerated rate, stars produce heavy elements opaque, expanding at an accelerated rate, stars produce only hydrogen and helium transparent, expanding very slowly, stars produce only hydrogen and helium