If the first day of the year (other than the leap year) was Sunday, it means that the year started on a Sunday. To determine the last day of that year, we need to determine the number of days in the year.

In a non-leap year, there are 365 days. Since 7 days make up a week, we can calculate the remainder when 365 is divided by 7. The remainder will tell us the number of extra days beyond complete weeks.

When we divide 365 by 7, the remainder is 1. This means that there is 1 extra day beyond complete weeks in a non-leap year.

Since the year started on a Sunday, and there is 1 extra day, the last day of the year will be the day that comes after Sunday. In this case, that day would be Monday.

So, the correct answer is option 1: Monday.

Note: It is important to note that this answer assumes that there are no other factors or events that could affect the determination of the last day of the year.