The answer to the question about the ideal water temperature for betta fish is letter C or between 72 to 80 degrees. Betta fish are tropical fish which are used to consistent warm water. According to an article entitled Water for Betta Fish, the ideal water temperature for betta fish is between 74 to 78 degrees Fahrenheit or 23 to 25 degrees Celsius.
Using the given information, the closest answer from the given choices is truly letter B. It is said that Betta fish should not be stored in container having a water temperature colder than 74 to 78 degrees Fahrenheit because it can destroy their immune system and they will be prone to illness and may result in their death.