Witch of the following contributed greatly to the fall of the song dynasty? a. the invention of gunpowder b. the increase in the chinese population c. the improvement of the civil service system d. the vulnerability to invaders from the north

the right answer is the vulnerability to invaders so D

Explanation: I took the test

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the of atp are the key to its ability to store and supply energy;

phosphate

the phosphate groups of atp are the key to its ability to store and supply energy. atp releases energy when it breaks bonds between its phosphate groups.