To determine the best temperature to heat the tea when adding sugar for maximum sweetness, you would refer to the solubility graph for sugar in water. Generally, sugar's solubility increases as temperature increases, meaning you can dissolve more sugar in hot water than in cold.
Among the options provided:
A. 55°C
B. 1414°C (not a realistic temperature for this context)
C. 1616°C (not a realistic temperature for this context)
D. 39°C
The best option for heating tea to dissolve sugar might be A. 55°C, as it is a reasonable temperature where sugar will have a significantly higher solubility compared to the other options like 39°C.
Therefore, the best answer is A. 55°C.