How does the evidence provided by the graph support the claim that Earth's climate has gradually been warming?

A. The rising sea level is a result of melting ice and the thermal expansion of water.
B. The rising sea level is a result of an increasing rate of all processes of the water cycle.
C. The change in sea level matches the change in atmospheric levels of carbon dioxide.
D. The change in sea level is the cause of increased flooding in low-lying coastal lands.