What does the left y-axis show? a - sea surface temperature anomaly, in degrees celsius

b - sea surface temperature anomaly, in degrees fahrenheit

c - time, in four-year intervals

d - incidence of cholera, as a percentage of the normal rate

e - sea surface temperature, in degrees celsius

The correct option is;

a - sea surface temperature anomaly, in degrees Celsius

Explanation:

From the diagram related to the question we have two graphs super imposed of Sea surface temperature anomaly, in degrees Celsius and cholera incidence anomaly (%) both plotted against time in years.

On the left the y-axis represents the sea surface temperature anomaly while on the right, the y-axis represents the cholera incidence anomaly (%).

The display of the graph shows the sea surface temperature anomaly in blue.