Final answer:
To convert days into a fraction of a year, divide the number of days by 365 (option A). This places the days as the numerator and the total number of days in a year in the denominator.
Step-by-step explanation:
The student asked what should go in the denominator of a fraction to change days into a part of an exact year (365 days). The correct answer is option A) 365. To express a certain number of days as a fraction of a year, you divide the number of days by 365, the total number of days in a non-leap year. For example, to convert 180 days into a fraction of a year, you would calculate 180/365.