Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because __________.

• A. the valence electrons in the phosphorus atom have less energy on average than those of other atoms
• B. they are hydrogen bonds, which are only about 10% as strong as covalent bonds
• C. the phosphate groups are polar and are attracted to the water in the cell's interior
• D. the bonds between the phosphate groups are unusually strong and breaking them releases free energy
• E. the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP