a) With the word access modifier "private" we are declaring that the method will only be accessible within that class (i.e you can not call the method from an external class/file). b) Since the value of the parameter "month" is 7, the first two "if/else" statements will be skipped and the value returned will be 31c)We could have logical error if we are trying to assign the value returned so a variable of a different type (i.e not int) or if we are not respecting the number and the type of the parameter. d)It can be used in methods such as calculating the date after a certain number of days/weeks/months/years.