How many months have exactly 30 days?

The reasoning behind the correct answer involves understanding the characteristics of the months in the Gregorian calendar, which is widely used today. In this calendar, there are four months that have exactly 30 days: April, June, September, and November. These months are distinct and do not have variations in the number of days during leap years or regular years.

To clarify, January, March, May, July, August, October, and December all have 31 days, while February typically has 28 days and 29 days in a leap year. Consequently, when counting the months with precisely 30 days, the total amounts to four. Thus, the correct choice is based on identifying the months that fit this specific criteria.