2. Under acidic conditions, bicarbonate acts as a buffer in seawater by bonding to additional ions, increasing the pH of the ocean.
O A. hydroxide
O B. carbonate
C. carbon dioxide
D. hydrogen

B.

Explanation:

The rise in the acids levels of the sea water is caused by the dissolve of CO2 in sea water which lowers the pH.The resultant unstable  compound(weak acid) formed is H2CO3.The latter dissociates to for HCO3 + CO3- These  reversible products are the buffers in the seawater that resists the fluctuation in the pH. The carbonate ions reacts with the high concentrations of  Ca + in the sea water, to form  the exoskeleton s of some  fauna.e.g.,Mussels.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]