Which statement is correct about the krebs cycle? a. oxygen is a waste product of the krebs cycle. b. acetyl-coa combines with pyruvic acid to make glucose in the krebs cycle. c. the krebs cycle produces electron carriers for the electron transport chain d. in the krebs cycle, carbon dioxide is used to make glucose.

i think that d. wind is the answer.   i missed the question when i answered a. currents.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.