Fill in the blank with the most appropriate option:Water at a temperature of 100^o C __________.

Answer: Option A

In this sentence, we are talking about the current state of water at a specific temperature (100 degrees Celsius). The present continuous tense "is boiling" is appropriate because it indicates that the water is currently in the process of boiling at that temperature.

The correct sentence should be: "Water at a temperature of 100^oC is boiling." This usage effectively conveys the ongoing action of boiling at the given temperature.