Carbon Dioxide (CO₂) Concentration in the Atmosphere Increased from 280

Carbon dioxide (CO₂) concentration in the atmosphere increased from 280 parts per million (ppm) in 1750 to 400 ppm in 2013. How has this change affected the oceans?

A) movement of CO₂ from the ocean to the atmosphere has decreased the pH of ocean waters
B) movement of CO₂ from the atmosphere to the ocean has decreased the pH of ocean waters
C) movement of CO₂ from the ocean to the atmosphere has increased the pH of ocean waters
D) movement of CO₂ from the atmosphere to the ocean has increased the pH of ocean waters