Which of the curves in the figure represents the relation between Celsius and Fahrenheit temperatures?

conversion between Celsius and Fahrenheit

F = temperature in Fahrenheit

°C = temperature in Celsius)

If we draw the graph between Fahrenheit and Celsius, the curve will lies in the fourth quadrant and it look like the below fig.

(Note: change the scale of x and y-axis to get the exact graph which is shown in the question.)

Thus, a is the correct answer.